Hooke's Law: Calculating Spring Constants 

 

Forces cause objects to move or deform in some way. Newton’s third law states that for every force, there is an equal and opposite force. This is true for springs, which store and use mechanical energy to do work.
Springs are elastic, which means after they are deformed (when they are being stressed or compressed), they return to their original shape. Springs are in many objects we use on a daily basis. They in ball point pens, mattresses, trampolines, and absorb shock in our bikes and cars. According to the Third Law of Motion, the harder your pull on a spring, the harder it pulls back. Springs obey Hooke’s Law, discovered by Robert Hooke in the 17^th century. Hooke’s law is described by:

F = -kx

Where F is the force exerted on the spring in Newtons (N),
k is the spring constant, in Newtons per meter (N/m),
and x is the displacement of the spring from its equilibrium position.
The spring constant, k, is representative of how stiff the spring is. Stiffer (more difficult to stretch) springs have higher spring constants. The displacement of an object is a distance measurement that describes that change from the normal, or equilibrium, position.

Problem

Calculate the spring constant using Hooke’s law.
Which spring do you think will have the greatest spring constant? The smallest spring constant? Why?

Materials

• Scale (measures grams or kilograms)
• Ruler (measuring centimeters)
• Different coil springs
• Small weight
• Wooden plank
• Table or countertop
• Books, or other stackable objects

Procedure

1. With the help of an adult, fix one end of each spring to one side of the wooden plank. Be sure to leave a couple of inches between each spring. Why should one end of the spring be fixed?
2. Arrange some books on a table or countertop in two stacks, about the length of the wooden plank.
3. Place the wooden plank on the stacks with the springs hanging down. Make sure there is still some room between the bottom of the springs and the table.
4. Using the centimeter side of a ruler, measure the equilibrium position of each spring.
5. Weigh the small weight on the scale and record its mass in kilograms. Why does the mass have to be in kilograms?
6. Attach the weight to each spring one at a time, and use the ruler to measure the displacement. An easy way to do this is to measure the length of the spring, and then subtract the equilibrium length.
7. Calculate the gravitational force exerted by the mass on the spring.

F_g = mg

Where F_g is the gravitational force, in Newtons, m is the mass of the weight, in kilograms, and g is the gravitational constant of Earth, equal to 9.81 m/s².
Set the gravitational force (F_g) equal to the force exerted by the spring (F). Why can you make these two variables equivalent? Use Hooke’s law to calculate the spring constant, k, for each spring.

Results:

Springs with larger spring constants will have smaller displacements than springs with lesser spring constants for the same mass added.

Why?

Hooke’s Law is a representation of linear elastic deformation. Elastic means that the spring will return to its original form once the outside force (the mass) is removed. Linear describes the relationship between the force and the displacement. The fact that the spring constant is a constant (it is a property of the spring itself), shows that the relationship is linear.
Of course, Hooke’s Law only remains true when the material is elastic. If a spring is permanently deformed (by something like crushing or overstretching), it will no longer return to its original position. If you have ever played with a slinky and accidentally stretch it too far or bent it out of shape, you’ll know that it doesn’t perform like it is supposed to afterward.
For Hooke’s Law to work properly, the parts of the equation have to be in the correct units. Without consistent units, the equation is meaningless.
You can set the gravitational force exerted by the mass on the spring equal to the force exerted by the spring due to Newton’s Third Law of Motion, which states that forces come in pairs. Every force has an equal and opposite force.

 

 

 

0

Physics of Pool: Elastic Collision of Equal Masses

The final shot in the pool game is yours, but the cue and the eight ball aren’t nicely lined up with any of the pockets. Looking around, the closest pocket is 45 degrees off the line between the two balls. You take aim for a glancing blow, the cue ball strikes the eight ball…what happens next? Do you sink the eight ball? Which way does the cue ball end up going? And how can you make the eight ball go off in a different direction?

Pool is a great example of physics in action. After every collision, the momentum of all the balls—the product of their mass and velocity—has to be conserved. That is, the total momentum before the collision has to be the same as the total momentum after the collision. And, roughly speaking, the energy must be conserved as well; the balls can’t fling away from each other with more energy than you give them. These two laws—the conservation of energy and the conservation of momentum—work together to steer the balls around the table.
In this project, you’ll experiment with colliding masses, see how they collide, and maybe learn how to use physics to plan the perfect pool shot!

Problem

At what angle will two equal-mass balls move away from one another after a glancing collision?

Materials

• 2 low friction masses of equal weight (hover pucks orair hockey pucks would work best)
• Smooth, flat surface (if using a pool table, try placing a foam board overthe surface to reduce friction)
• Protractor
• Tape
• String

  Procedure

• Place one puck on the surface and mark its starting position with the tape.
• Place the second puck a foot or so away from the first puck.
• Gently push the second puck towards the first puck, aimed so that it hits the puck at a glancing angle rather than straight on (this may take a few practice runs).
• Mark a couple of points along the paths both pucks tookafter the collision.
• Using the marks as a guide, lay a lengthof string along each of the paths taken by the pucks.
• Use the protractor to measure the angle between the strings—the angle at which the pucks moved away from each other.
• Repeat steps 1-6 several times and calculate the average angle between the strings. If the puck doesn’t hit at a glancing angle, then just skip that attempt and try again.

Results

The angle between the pucks’ paths will be close to ninety degrees—a right angle.

Why?

In an elastic collision, both momentum and kinetic energy are conserved. Momentum is given by mvand kinetic energy by ½mv², where m is mass and v is velocity. If ​​v_crepresents the velocity of the moving puck before the collision, ​​v_ais the velocity of the moving puck after the collision, and ​​v_bis the velocity of the stationary puck after the collision, then conservation of kinetic energy leads to:

½mv_c²=​½mv_a² + ​½mv_b²

Because all the masses are equal, the m’s cancel and you end up with:

v_c²=v_a^{2 +}v_b²

This equation has the exact same form as the Pythagorean Theorem, c² = a²+ b²​where a and b are the sides of a right triangle and c is the hypotenuse. This only works if v_aand v_bare at right angles to one another.

 
The conservation of momentum adds some depth (and complexity). Momentum is a little more complicated because it has to be broken down into components: the momentum along the original direction of motion (x) and momentum perpendicular to that direction (y). Momentum in both directions has to be conserved. Initially, all the momentum is in the x direction:

mv_cx = mv_ax + mv _bx

Canceling the masses, you end up with

v_cx = v_ax + v _bx

In the y direction, there is initially no momentum. To make everything balance, that means the y-direction momentums after the collision must perfectly cancel:

mv_cy = 0 = mv_ay + mv _by

0 = v_ay + v _by

v_ay = -v _by

Putting this together with the conservation of energy, you find that all the velocity components after the collision have the same magnitude, with the y components pointing in different directions. You end up with the final velocities pointing at right angles away from each other.
In an inelastic collision, kinetic energy is not conserved; some energy is lost to the surroundings. This means that, while the ycomponents of the velocity still have to cancel, the xcomponents can be different. The balls will no longer bounce away at right angles.
In reality, perfectly elastic collisions rarely happen; some energy is always lost. Collisions between subatomic particles (protons and electrons) are very nearly elastic; so are atoms in an ideal gas. Space probes that slingshot around a planet behave the same way as elastic collisions as well.

Going Further

What happens if you use pucks (or balls) with different masses? For example, if you’re using air hockey pucks, try making the stationary puck be two pucks stacked on top of one another. What changes?
What happens if you use a surface that isn’t smooth (for example, a carpet)? How does that change the angle? Is it less than or more than a right angle? Can you explain what you’re seeing using the equations mentioned above?

0

Evaluating Choice Blindness: Do You Know What You Want?

“Choice blindness” refers to the phenomenon where people are blind to their own choices or preferences and are able to validate decisions they did not actually ever make. This experiment will evaluate whether men or women are more likely to demonstrate choice blindness.

Problem:

This experiment will evaluate whether the phenomenon of “choice blindness” occurs more often with men or women.

Materials:

• Approximately 30 test subjects (15 men and 15 women)
• 20 photos of non-celebrity, unknown (to test subjects) males
• 20 photos of non-celebrity, unknown (to test subjects) females
• Notebook for recording results
  

  Procedure

• Recruit 15 male and 15 female adult test subjects.
• Print 20 photos of non-celebrity, unknown males and 20 photos of non-celebrity, unknown females. The photos should be headshots that are approximately the same size, zoom, brightness, etc.
• Present two male photos side by side and ask a female test subject to tell you which person she finds more attractive.
• Take both photos away and present her with her chosen photo. Ask her to tell you why she chose that image.
• Record her answer.
• Repeat steps 3-5 ten times with the female test subject using different pairs of faces each time. In three of the trials, however, exchange one face for the other after the test subject makes her choice. In these three trials, closely observe your test subject. Does she notice that she is presented with the photo that she did not choose? Is she able to give a reason why she chose that photo (even though she actually did not choose the photo)?
• Repeat this experiment withall of your male and female test subjects. For your male test subjects, use the non-celebrity, unknown female photos that you chose.
• Analyze your results. How many times were you able to fool your female test subjects by presenting them with photos they did not choose? How many times were the male test subjects fooled? What conclusions can you draw about choice blindness in men and women?

0

Density Experiment

Density refers to the amount of stuff there is in a given space. Different things have different densities. For example, a cup of water has more stuff in it than a cup of oil. The water is denser. A marble and a ball of the exact same size are made of different amounts of stuff – they have different densities. Do you think the less dense oil will sink in or float on the denser water? Which is denser, the marble or the ball? How can you tell?

Problem:

How do liquids of various densities interact with each other?

Materials:

• Measuring cup
• Clear glass jar (labels removed)
• ½ cup water
• Food coloring
• ½ cup corn syrup
• ½ cup vegetable oil
• Marble
• Small rubber ball of approximately the same size as marble
• Circle of carrot, mini marshmallow, other small objects

Procedure

1. Pour the water into the jar.
2. Color it with food coloring.
3. Pour the corn syrup into the jar. What happens?
4. Carefully pour the oil into the jar. What happens?
5. Drop the marble into the jar. Does it float? Sink?
6. Drop the ball into the jar. Does it float? Sink?
7. Continue dropping objects into the jar and observing what happens.
8. What can you tell about the densities of the liquids and the objects?

0

Does the Amount of Air Inside the Ball Affect How Far It Goes?

Objectives

To determine whether the amount of air in a soccer ball will affect how far it goes when kicked.

 

Materials and Equipment required

• Soccer ball
• Ball pump
• Ball pressure gauge
• Tape measure meter or yardstick
• Inflation needle
• Glycerin oil
• Roll of gym floor tape
• Marker
• Pen
• Graph paper
• Data chart

Introduction

This soccer science fair project serves to acquaint students with basic information on how the amount of air in a soccer ball can affect the distance it travels when kicked with a consistent force. The greater the air pressure in the ball, the farther it will travel when a force is applied. In the process of conducting the research, the student will learn that atmospheric pressure may also affect how far the ball will travel. The student will learn about the relationship between air pressure and friction: the lower the friction, the farther the ball will go. The student will learn about concepts like air pressure, gravitational force, compression and expansion of air molecules, potential energy and kinetic energy.
This science fair experiment also serves to acquaint students with the essential processes of scientific inquiry such as using a control, of identifying dependent and independent variables, collecting data, presenting data, and making good judgments about the validity and reliability of their findings.

Research Terms

• air
• friction
• forces
• air pressure
• compression of air molecules
• expansion of air molecules
• gravitational force
• energy
• kinetic energy
• pressure gauge
• air pump

Research Questions

• How do we measure air pressure?
• How much air pressure is there at sea level?
• How is air pressure inside the ball related to the distance the ball will travel?
• What happens to the air pressure inside the ball when it is kicked?
• Will the atmospheric pressure affect the distance the ball will travel?
• Does friction affect the distance the ball will travel?

Terms, Concepts and Questions to Start Background Research:

• What is a control? A control is the variable that is not changed in the experiment.
• What purpose does a control serve? It is used to determine what the variable changed.
• What are variables? Variables are factors that can be changed in an experiment.
• What is an independent variable? The independent variable is the one that is changed in the experiment.
• What is a dependent variable? The dependent variable is the one that changes as a result of the change in the independent variable.

Experimental Procedure

1. State the problem you are going to investigate in this science fair project.
2. Create and reproduce the data sheets you will use to record your observations.
3. Gather all your materials.
4. Select a helper (another student or a parent) to assist you in gathering the data.
5. Use the gym floor tape and mark the path along which you will kick the ball.
6. Select three air pressure levels for the ball, designating them as low, medium and high. Using the pressure gauge, double check the pressure in the soccer ball each time you change the pressure. Caution: When kicking the ball, try to kick with the same force each time. Have your partner mark the spot where the ball lands each time. Then, measure the distance and record the data in your chart. Repeat the procedure 3 times at each pressure level and then average and record the results for each level.
7. Make a line graph of the data, recording differences in pressure on the Y axis and the distance travelled on the X axis.
8. Record your conclusion and prepare your report. Include all of the following: a clear statement of the problem, your hypothesis, and a list of the materials used. Include any safety precautions taken. Describe the procedures used. Include all the data that were gathered, including all charts and graphs. For dramatic value, you may include photos of the materials used or of you in the process of conducting this investigation. Include a bibliography of sources you used. You may wish to assess what you did and describe what you would do differently if you were to do this project again. You may wish to expand this research next year. What other experiments might you use to investigate the physics of a soccer ball?

Charting and or Graphing Data

In each section of the experiment, use charts to display the obtained data such the following sample:

Chart #1 : Observations: How far did the ball go?

Pressure in soccer ball in PSI	Distance Travelled in cm.
High #1
High #2
High#3
Medium #1
Medium #2
Medium#3
Low #1
Low#2
Low#3

Chart #2: Average Data

Pressure	Averages
High PSI
Medium PSI
Low PSI

0

Can You Cook Using Only Sunlight?

Grade Level: 7th to 11th; Type: Meteorology, Physics

Objective:

Bake cookies with an oven that collects sunlight and traps heat.

• How can I cook using just sunlight?

Make an oven that collects sunlight and traps the shorter wavelengths (heat!) inside the same way greenhouse gases in our atmosphere trap them, and bake some cookies!

Materials:

• Two cardboard boxes: one must fit completely inside the other with about an inch or two to spare, and the outer one must have flaps (or you can create and attach some)
• Roll of aluminum foil
• Masking tape
• Four 12-inch pieces of string
• Eight beads or pieces of macaroni
• Pencil
• Piece of black construction paper
• Scissors
• Scrunched-up shredded paper
• Piece of glass, large enough to completely cover the smaller box but small enough to fit inside the larger one
• Cooking thermometer
• Small cookie sheet or pie tin (must fit inside smaller box; make your own with some of the foil if necessary)
• Prepared cookie dough (commercial or homemade) that bakes at 350° or under warm, sunny day

Experimental Procedure

1. Cover the insides of the flaps of the larger box with aluminum foil, with the shiny side facing out; tape the foil in place. Use the pencil to poke small holes in the edges of the flaps.
2. Tie a bead to one end of one of the pieces of string, string it through one of the holes in one of the flaps so that the bead ends up on the outside of the flap, string it through the hole in the next flap over from the inner side to the outer, and tie another bead to this end of the string. Repeat so that all four flaps are connected together with the strings.
3. Line the entire inside of the smaller box with foil, shiny side out, taping it in place.
4. Cut the piece of construction paper so that it fits neatly inside the smaller box; tape it inside the bottom of the box.
5. Put enough shredded paper inside the larger box so that when you rest the smaller box on it, the opening is just barely below the opening of the big box.
6. Center the little box and pack the space between the walls of the big box and the walls of the little box with more shredded paper.
7. Put the cooking thermometer and some of the cookies on the baking sheet (you may need to grease it first: check the instructions/recipe) and set it inside the inner box; cover the inner box with the pane of glass. Your solar oven is ready to go!
8. Take the oven outside and set it in a bright, sunny spot where it won’t be disturbed. Turn it so that the sun shines directly into it; if the sun isn’t pretty close to directly overhead, you might want to put something under one side of the box to tip it to face the sun. Use the strings to adjust the flaps so that as much sunlight as possible is reflected into the inside of the oven.
9. Now you wait. I hope you brought a good book! Depending on the time of day and how warm it is outside, you may need to turn the oven or even move it to a new spot so that it gets as much sunlight in it as possible.
10. Keep an eye on the cooking thermometer. You’ll notice that it gets much hotter inside the oven than it is outside. That’s partly because the aluminum foil is focusing the solar radiation, and partly because the glass is acting like a layer of greenhouse gases: like them, it’s clear, but some of the shorter wavelengths will bounce off of it and tend to stay inside the oven, making things hotter and hotter inside. It may get as hot as 350° Fahrenheit in there!
11. When the cookies look like they’re about done (they’ll probably be browning around the edges and won’t be shiny anymore), or when the thermometer reads a temperature higher than they’re supposed to cook at, whichever comes first, take the glass off and let the inside of the oven cool for a few minutes. When the cookie sheet isn’t too hot to touch anymore, lift it out and try a cookie!

Terms/Concepts: solar radiation, greenhouse gases

0

Crystal Fudge

Grade Level: 8th to 12th; Type: Geology

Objective:

Find out what happens when the fudge crystallizes at different temperatures.

Research Question:

• Why do some rocks that are made out of the same minerals have different-sized crystals in them?
• What effect will faster vs. slower cooling have on the formation of crystals?

Fudge is one of very few desserts people make at home that is actually crystalline, or made out of crystals. This gives us a fun, tasty way to explore the process of crytalization.

Materials:

• Two bread pans (disposable 8” pie tins will also work)
• Butter to coat pans, or waxed paper
• Large saucepan (3-4 quart)
• Wooden spoon
• Candy thermometer
• Pastry brush
• Stove
• Refrigerator
• 3oz. unsweetened chocolate
• 3c sugar
• 1c warm half-and-half or evaporated whole milk
• 1T corn syrup ¼t salt
• 3T butter
• 2t vanilla extract
• 1c mix-ins of your choice: nuts, mini marshmallows, dried fruit… (optional)
• Magnifying glass

Experimental Procedure

• Butter the pans or line them with the waxed paper.
• Mix the chocolate, sugar, salt, half-and-half, and corn syrup over medium-low heat. Keep stirring until the chocolate is melted and the fudge begins to boil. Note: the fudge is extremely hot at this point, handle with care!
• As soon as the fudge begins to boil, stop stirring and put the candy thermometer in. Clip it to the edge of the pot, making sure the tip isn’t touching the bottom.
• Let the fudge cook without any stirring until it reaches the soft-ball stage, around 237 degrees.
• While the fudge cooks, dip the pastry brush in a little warm water and use it to carefully wash any sugar/chocolate/whatever off the sides of the pot.
• Take the fudge off of the burner and let it cool, undisturbed, until it’s 150 degress.
• Add the vanilla and butter and keep stirring until the surface of the fudge starts to get dull. This can take a long time, but you need to keep stirring! Maybe you can get a partner to help.
• Once the fudge has begun to dull, stir in your add-ins, a quarter-cup at a time, if you’re using any. Make sure they’re at room temperature or a little warmer if possible.
• Spoon half of the fudge into each pan. Put one pan in the refrigerator and leave the other one out at room temperature. Allow both of them to cool completely.
• Cut each panful of fudge into one-inch cubes. Pick up a cube from each pan and examine them closely. Use your eyes and the magnifying glass: do you see any differences in texture? Use your tongue: does one seem more smooth and waxy while the other is more grainy? Is there a difference in flavor? The fudge that cooled more slowly, at room temperature, should be grainier and have noticeable sugar crystals in it. This is like a plutonic igneous rock that has cooled and solidified slowly, under the surface, like granite. The one that cooled more quickly, in the refrigerator, should be smoother and have much smaller crystals, probably too small for you to see even with the magnifying glass. This is like a volcanic igneous rock that cooled quickly above the earth’s surface, like obsidian.
• Now offer samples of each to your family and friends so they can decide which they like best!

Terms/Concepts: igneous rock; crystallography, crystal formation

0

What Music Does Bacteria Enjoy the Most?

Grade Level: 9th to 12th; Type: Biology

Objective:

This experiment will explore whether music of different varieties affects the growth of bacteria.

Research Questions:

• Does music alter the growth of bacteria?
• Do different kinds of music make the bacteria grow differently?

Although bacteria lack the ability to hear, they are very perceptive to changes in vibration. Physically speaking, music is essentially various changes in vibration. This experiment might help figure out better ways to process sewage and other essential microbe-assisted duties.

Materials:

• 2 or more prepared Petri dishes with agar (available from biological supply companies)
• Sterilized swabs
• Rubber or plastic gloves
• 2 or more portable CD or MP3 players
• Several pairs of cheap headphones, NOT earbuds (same number as music players) You will want to throw them away after the experiment.
• Several songs or albums of various music, the more diverse the better (such as classical, hard rock, and dance)
• Camera
• Notepad and paper
• Ruler

Experimental Procedure

1. Wearing gloves, prepare the Petri dishes. Following the manufacturer’s instructions, take them out of the refrigerator for about an hour before conducting the experiment.
2. Using the sterilized swabs, collect bacterial samples while wearing gloves. Good places to nab some bacteria include faucets or any other area that is touched by a lot of people. Ensure that you swab from the same area to get roughly the same amount and type of bacteria. Swipe the swab against the agar in the Petri dish and then close and seal the dish. Label each sample.
3. Place the samples in a warm, out of the way place. Leave one sample alone, this is the control.
4. For the other samples, place the headphones snugly around the dish.
5. Connect the headphones to the music players. Play a different song or album on repeat on each player.
6. Let the samples grow for a week. Make sure to keep the music players charged and playing at all times. Take pictures of the developing bacteria everyday.
7. Take off the headphones and compare each sample. Take note of the amount of colonies in each sample and measure the size of each colony.
8. Carefully dispose of the Petri dishes.
9. Analyze this data. Did the music have an affect on the size or amount of bacteria colonies? Did a certain genre of music have a greater affect than others?

Terms/Concepts: microbiology, bacteria, microbes, vibrations, sewage treatment

0

Laser Jet Toner: a Magnetic Fluid

Grade Level: 7th to 9th; Type: Physical Science

Objective:

In this experiment, you will experience a magnetic fluid as it moves, bubbles, and forms unique shapes.

Research Questions:

• Why does the fluid contort into different shapes?
• Are there other fluids that are magnetic?
• What makes them magnetic?

Materials:

• Magnets of varying size and strength
• Laser jet toner (Ferro fluid)
• Beaker
• Pure vegetable oil
• Stirring stick
• Long, clear bottle, jar or flask

Experimental Procedure

1. Pour 50mL of toner into the beaker.
2. Pour in 30mL of pure vegetable oil.
3. Stir it to a nice thin consistency. (If it is too thin, it might not work properly.)
4. Pour the mixture into the long container.
5. Touch a magnet to the container. Observe what happens to the fluid. (It should move with the magnet and contort into intriguing shapes.)
6. Experiment with using other magnets. See what happens when you drop the magnets into the liquid.

Terms/Concepts: magnetism, magnetic fluid

0

When Air Masses Collide

Grade Level: 7th to 10th; Type: Meteorology
Objective:
Use hot and cold water to simulate what happens when a warm front meets a cold one.

Research Questions:

What happens when a warm air mass meets a cold one?

Materials:

• Pencil and paper
• 10-gallon aquarium
• Piece of cardboard
• Scissors
• Stirrer (a wooden spoon or a ruler would be great)
• Five gallons of very cold water
• Blue food coloring
• Five gallons of very hot water
• Red food coloring
• Timer or clock
• Latex gloves
• Red colored pencil, crayon, or marker
• Blue colored pencil, crayon, or marker

Experimental Procedure

1. Use the pencil to draw seven large rectangles that look something like the aquarium on the piece of paper. Label the seven rectangles “0 minutes,” “1 minute,” “3 minutes,” “5 minutes,” “7 minutes,” “10 minutes,” and “15 minutes.”
2. Cut the piece of cardboard so that it just barely fits inside the aquarium, dividing it in half the short way. It should be very snug; it needs to keep the water on one side from mixing with the water on the other side for a minute or so. But don’t use any tape to keep it in place, it needs to come out easily!
3. With the cardboard snugly in place, fill half of the tank with the very cold water. (If it’s ice water, so much the better, but don’t get any ice in the aquarium.) Put a few drops of blue food coloring in the water and stir it; repeat as needed until you’re happy with the color. This is going to represent the cold front, or mass of cold air.
4. Now carefully fill the other half of the aquarium with very hot water and stir in some red food coloring. This is your warm front, or warm air mass.
5. Quickly draw a picture of what the tank looks like now by using the red and blue pencils to fill in the rectangle marked “0 minutes.”
6. Put on the gloves and quickly and carefully remove the sheet of cardboard. Try not to stir the water up too much in the process. Set the timer for one minute, remove the gloves, and watch what the water does until the timer rings.
7. Set the timer for two more minutes, then quickly draw a picture of what the water looked like at the one-minute mark in the rectangle labeled “1 minute.”
8. When the timer rings, set it for two more minutes and sketch what the tank looked like at the three-minute mark.
9. Repeat, setting the timer for the appropriate number of minutes (watch out, that changes toward the end) until you’ve filled in all of your rectangles.
10. Now look at your pictures. What did the “air masses” do? Did they mix right away? Was there a sharp division between them, or did the water combine and make a purple layer? Did the air masses stay side by side as they blended, or did one rise while the other sank? Why do you think the cold and warm fronts behaved the way they did?

Terms/Concepts: air mass, warm front, cold front

0

How Does Microwave Radiation Affect Different Organisms?

Grade Level: 9th to 12th; Type: Biology

Objective:

This experiment will determine how microwave radiation affects fungi, bacteria, and plant life.

Research Questions:

• Does microwave radiation destroy all life?
• Will varying lengths of radiation affect organisms differently?

Microwave ovens blast food with high levels of energy. This results in heating up certain fats and other ingredients in food. The energy simply passes through other substances without damage. Through this experiment, we will see how this energy affects simple organisms of different types.

Materials:

• Packet of radish seeds
• Paper towels
• Four small containers filled with sterilized potting soil
• Four packets of bakers’ yeast
• Four small bowls
• Four prepared Petri dishes with agar (available from biological supply companies)
• Sterilized swabs
• Gloves
• Microwave
• Notepad and pen
• Camera

Experimental Procedure

1. Plant several radish seeds in a small container. Put them in a sunny, warm location. This is the control sample.
2. Place several more radish seeds on a paper towel. Microwave the seeds for five seconds.
3. Plant these seeds in another pot and place in the same location as the control group.
4. Repeat Step 2 and 3 for two more samples, except microwave one group of seeds for fifteen seconds and the other for thirty seconds.
5. Tend the samples by watering the pots once a day and ensuring they get enough sunlight.
6. Take pictures everyday and note if and how quickly the samples grow.
7. Dump a packet of bakers’ yeast into a small bowl of warm water. Stir. This is the control sample.
8. Take note of how long it takes for the yeast to bubble up and how vigorous the reaction is. Take photos.
9. Dump another packet of bakers’ yeast onto a plate. Microwave for five seconds.
10. Mix this yeast into another bowl of warm water. Repeat Step 8.
11. Repeat steps 9 and 10 for the other packets of yeast, except microwave one sample for fifteen seconds and the other for thirty seconds.
12. Wearing gloves, use the sterilized swab to collect a sample of bacteria and swab it on a prepared Petri dish. Good places to find bacteria are areas where lots of people touch something, like doorknobs or faucets. Seal the dish and label it “control.” Put it in a warm, dark place. This is your control sample.
13. Swab another sample from the exact location as the control sample. Smear it on another Petri dish. Seal and label the dish. Place it in a warm, dark place.
14. Repeat Step 13 for the other two samples.
15. Let the samples alone overnight.
16. Take one sample out (not the control) and microwave it for five seconds. Place it back in the warm, dark place.
17. Repeat Step 16 for the other two samples, except microwave one for fifteen seconds and the other for thirty seconds.
18. After another day, take out all the samples. Note how many colonies of bacteria are growing and their size.
19. Analyze all this data. Does microwave radiation affect all life equally? Does time matter? How does each type of organism respond to the radiation?

Terms/Concepts: Microwaves, microbiology, radiation

0

Does Hair Color Affect Perception of Intelligence?

Grade Level: 6th - 9th; Type: Behavioral Science

Objective:

In this experiment, we will investigate whether hair color changes peoples' perception of intelligence.

Research Questions:

People believe in many stereotypes, such as that blondes are dumb. In this experiment, we'll change the hair color of people in photographs in order to see how it affects percpetions of intelligence.

Materials:

• Random, clear photos of people of the same race.
• Image-editing software like Adobe Photoshop
• Computer and printer
• Test subjects (the more the better)

Experimental Procedure

1. Find some random facial photos of people. Note the original color of the person's hair.
2. Open an image editing program, like Photoshop, and change the color of the person's hair to brunette, blonde, black, and red. (This guide will tell you how to do this in Photoshop: http://tutorialblog.org/photo-retouching-change-hair-color/ )
3. Remember to save a copy of the photo in each hair color.
4. Do the above for all your photos.
5. Print the photos out.
6. Ask your test subjects which person looks smarter in the series. Jot down their answer.
7. Evaluate which hair color generally got the most recognition for being “smart-looking”.

Suggested Chart

	Which Hair Color Was Said To Look the Smartest?
Series #1
Series #2
Series #3
Series #4

Terms/Concepts: Hair color; Intelligence Quotient; Perception

0

Does Chewing Gum Help You Concentrate?

Grade Level: 6th to 12th; Type: Social Science, Psychology, Health and Medicine

Objective:

This project explores whether chewing gum can help a majority of people with focus and concentration.

Research Question:

• Does chewing gum increase people’s speed and accuracy on simple cognitive tasks?

Educators have found that chewing gum can help children struggling with problems related to ADD/ADHD (Attention Deficit Disorder/Attention Deficit Hyperactivity Disorder). Is it possible that chewing gum can help all of us with focus and concentration?

 

Materials:

• Computer, printer, and paper
• Pencils for test-taking
• Chewing gum
• Timer
• Test subjects
• Paper and pencil for recording and analyzing data

Experimental Procedure

1. Write and print copies (one copy per test subject) of two simple subtraction worksheets.
2. Have subjects do each of the two worksheets. Subjects should chew gum while doing ONE of the worksheets.
3. Record how long it took each subject to complete each worksheet.
4. Score the worksheets for number of problems correct.
5. Analyze your results. Did chewing gum increase people’s speed and accuracy on subtraction tests?
6. Try the experiment in different environments, with different test subjects, and under different circumstances, keeping in mind these questions and any others that come up in the course of your research:
   • Does chewing gum make more of a difference in certain environments (e.g. noisy, crowded, or otherwise distracting environments)?
   • Does chewing gum make more of a difference to people of certain ages or genders?
   • Does chewing gum make more of a difference at certain times of day (e.g. early morning or late afternoon)?
   • Does chewing gum make more of a difference before or after certain activities (e.g. just before lunchtime or after physical exercise)?

Terms/Concepts: chewing gum, concentration, focus, ADD, ADHD

0

how to Turn Hand Warmers into Hot Ice Sculpture

Grade Level: 7th to 9th; Type: Chemistry

Objective:

This experiment provides a graphic illustration of the chemical reaction that transpires when you activate a hand warmer.

Research Questions:

• What is in hand warmers?
• How do hand warmers work?
• Why does the “hot ice” form in thie experiment?

Hand warmers provide instant heat on a cold day. They're also useful for making sculpture!

 

Materials:

• Five Reusable Hand Warmers
• Scissors
• Plate
• Bottle

Experimental Procedure

1. Activate one of the hand warmers.
2. When it turns white and stops giving off heat, cut it open and remove a single crystal.
3. Place the crystal on a plate.
4. Cut open the other four hand warmers and pour their contents into the bottle.
5. Carefully pour the contents of the bottle onto the crystal. Watch the effect. Voila! You are a modern artist!

Terms/Concepts: exothermic, endothermic, chemical instances

0

Vegetable Power

Grade Level: 6th - 9th; Type: Physical Science
To see if an LED light can be powered by vegetables and/or fruits.
The purpose of this experiment is to determine whether there is enough energy stored in a fruit or a vegetable to power an LED light. This experiment can be taken further to determine how long a fruit or vegetable can power an LED for.

• How is energy stored in a fruit or vegetable?
• How to we measure this type of energy?
• How do we usually use the energy stored in plants?
• Where do plants get their energy from?
• How much energy is stored in a typical potato?
• How much energy is stored in the other fruits or vegetables you are using?

With the help of a few household items, a potato can be used to power a light bulb. All living organisms contain energy and it may be possible to tap into and use some of that energy in our everyday lives. Given that our main source of energy, fossil fuel, is in limited supply, it is important for scientists to explore the use of alternative energy sources. Many natural, green energies are already being used around the world, but there is still a lot to learn about utilizing alternative energy sources. By developing planet-friendly ways to draw energy from the world around us, we can decrease our use of polluting energy sources which will help keep the air, water and soil clean for future generations.

• LED light bulb
• Assorted fresh fruits and vegetables (i.e. carrot, apple, pear, squash, lemon)
• 1 potato
• 1 shiny penny
• 1 galvanized steel nail
• 2 eight inch lengths of copper wire
• A knife

The materials needed for this experiment can be found at the grocery store and at the hardware store.

:

1. Begin by constructing a potato light. We already know that potatoes can be used to power LED lights, and setting up a working light in a potato will help you determine whether you are constructing the vegetable powered light correctly.
2. Make an incision in one side of the potato just large enough for the penny to fit inside.
3. Wrap one end of a piece of copper wire around the penny.
4. Wrap one end of another piece of copper wire around the nail.
5. Insert the penny into the slit you created for it, with the loose end of wire hanging out.
6. Insert the nail into the other side of the potato with the loose end of wire hanging out.
7. Do not allow the penny and nail to touch.
8. Wrap the copper wire coming off the penny to the longer leg of the LED.
9. Wrap the copper wire coming off the nail to the short leg of the LED.
10. Observe the results.
11. Repeat steps 2-10 with other vegetables or fruits.

Terms/Concepts: Green energy; Fossil fuel; Alternative energy; Potential energy; Filament; LED light

0

How To Do Flame Tests

Flame Test Introduction

The flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic color the salt turns the flame of a Bunsen burner. The heat of the flame excites the electrons of the metals ions, causing them to emit visible light. Every element has a signature emission spectrum that can be used to differentiate between one element and another.

How to Do the Flame Test

Classic Wire Loop Method
First, you need a clean wire loop. Platinum or nickel-chromium loops are most common. They may be cleaned by dipping in hydrochloric or nitric acid, followed by rinsing with distilled or deionized water. Test the cleanliness of the loop by inserting it into a gas flame.

If a burst of color is produced, the loop is not sufficiently clean. The loop must be cleaned between tests.

The clean loop is dipped in either a powder or solution of an ionic (metal) salt. The loop with sample is placed in the clear or blue part of the flame and the resulting color is observed.
Wooden Splint or Cotton Swab Method
Wooden splints or cotton swabs offer an inexpensive alternative to wire loops. To use wooden splints, soak them overnight in distilled water. Pour out the water and rinse the splints with clean water, being careful to avoid contaminating the water with sodium (as from sweat on your hands). Take a damp splint or cotton swab that has been moistened in water, dip it in the sample to be tested, and wave the splint or swab through the flame.

Do not hold the sample in the flame as this would cause the splint or swab to ignite. Use a new splint or swab for each test.

How to Interpret Flame Test Results

The sample is identified by comparing the observed flame color against known values from a table or chart.
Red
Carmine to Magenta: Lithium compounds.

Masked by barium or sodium.
Scarlet or Crimson: Strontium compounds. Masked by barium.
Red: Rubidium (unfiltered flame)
Yellow-Red: Calcium compounds. Masked by barium.

Yellow
Gold: Iron
Intense Yellow: Sodium compounds, even in trace amounts. A yellow flame is not indicative of sodium unless it persists and is not intensified by addition of 1% NaCl to the dry compound.
White
Bright White: Magnesium
White-Green: Zinc
Green
Emerald: Copper compounds, other than halides. Thallium.
Bright Green: Boron
Blue-Green: Phosphates, when moistened with H₂SO₄ or B₂O₃.
Faint Green: Antimony and NH₄ compounds.
Yellow-Green: Barium, manganese(II), molybdenum.
Blue
Azure: Lead, selenium, bismuth, cesium, copper(I), CuCl₂ and other copper compounds moistened with hydrochloric acid, indium, lead.
Light Blue: Arsenic and come of its compounds.
Greenish Blue: CuBr₂, antimony
Purple
Violet: Potassium compounds other than borates, phosphates, and silicates. Masked by sodium or lithium.
Lilac to Purple-Red: Potassium, rubidium, and/or cesium in the presence of sodium when viewed through a blue glass.

Limitations of the Flame Test

• The test cannot detect low concentrations of most ions.
• The brightness of the signal varies from one sample to another. For example, the yellow emission from sodium is much brighter than the red emission from the same amount of lithium.
• Impurities or contaminants affect the test results. Sodium, in particular, is present in most compounds and will color the flame. Sometimes a blue glass is used to filter out the yellow of sodium.
• The test cannot differentiate between all elements. Several metals produce the same flame color. Some compounds do not change the color of the flame at all.

Primary Reference: Lange's Handbook of Chemistry, 8th Edition, Handbook Publishers Inc., 1952.

Flame Test Colors

Symbol	Element	Color
As	Arsenic	Blue
B	Boron	Bright green
Ba	Barium	Pale/Yellowish Green
Ca	Calcium	Orange to red
Cs	Cesium	Blue
Cu(I	Copper(I)	Blue
Cu(II)	Copper(II) non-halide	Green
Cu(II)	Copper(II) halide	Blue-green
Fe	Iron	Gold
In	Indium	Blue
K	Potassium	Lilac to red
Li	Lithium	Magenta to carmine
Mg	Magnesium	Bright white
Mn(II)	Manganese(II)	Yellowish green
Mo	Molybdenum	Yellowish green
Na	Sodium	Intense yellow
P	Phosphorus	Pale bluish green
Pb	Lead	Blue
Rb	Rubidium	Red to purple-red
Sb	Antimony	Pale green
Se	Selenium	Azure blue
Sr	Strontium	Crimson
Te	Tellurium	Pale green
Tl	Thallium	Pure green
Zn	Zinc	Bluish green to whitish green

0

How Fires Burn in Different Colors

Grade Level: 7th to 9th; Type: Chemistry

Objective:

In this experiment you will observe fire burning in different colors.

Research Questions:

• Why do you think each fire burns a different color?
• Which color do you think is the hottest?
• Which color do you think is the coldest?

Materials:

• Menthol
• Epsom salt (Magnesium Sulfate)
• No salt - salt substitute (potassium chloride/bitartrate)
• Borax (boric acid)
• Bowl
• Lighter torch

Experimental Procedure

• WHITE

1. Pour 1/4 cup of magnesium sulfate into the bowl.
2. Pour 1/2 cup of the menthol into the bowl.
3. Light the mixture with the lighter torch.
4. Observe.

• BLUE VIOLET

1. Pour 1/4 cup of potassium chloride/bitartrate into the bowl.
2. Pour 1/2 cup of menthol into the bowl.
3. Light the mixture with the lighter torch.
4. Observe.

• GREEN

1. Pour 1/4 cup of boric acid into the bowl.
2. Pour 1/2 cup of menthol into the bowl.
3. Light the mixture with the lighter torch.
4. Observe.

Terms/Concepts: flame test, elements
References: Flame Tests:  How To Do Flame Tests

0

Soap Science

Type

Chemistry

Grade Level

4 & up

Difficulty Level

Medium

Cost

Minimal

Safety Issues

Adult supervision strongly recommended when using a microwave oven, and when working with potentially harmful chemicals.

Material Availability

All necessary materials are readily available.

Project Time Frame

3-4 weeks.

Objective

This project involves experiments with soap.The goals of this project are:

1. To identify the active ingredients in soap.
2. To experiment with the properties of soap.

1. Computer with internet access
2. Digital camera
3. Typical office/craft/hobby supplies (such as paper, pens & poster-board, wood, glue, etc.)
4. At least 4 bars of soap (different brands)
5. Bowls of water
6. Paper towels
7. Microwave oven

All materials can be found in your home, at local stores, or on ebay.

Introduction

Soap is a cleaning agent that’s been around for many centuries.The earliest form of soap was derived from various types of plants known to have cleansing properties, usually when mixed with water.These types of plants are known collectively as “soap plants.”In this project we examine the properties and uses of soap.

Research Questions

1. What are the active ingredients in soap?
2. What determines the quality of soap?
3. What are some of the best selling brands of soap?
4. How is soap manufactured?

Terms and Concepts to Start Background Research

• Density
• Soap Plants

1. Research related materials (see bibliography below and search terms listed above)
2. Remove each bar of soap from its packaging, and photograph each bar next to its packaging.
3. Weigh each bar of soap, and record all ingredients listed on packaging.
4. Fill 2 bowls with water.
5. Place all the bars of soap in one bowl, and notice which ones float and which ones sink.Try to determine why.
6. To the other bowl, add ½ teaspoon of black pepper from any ordinary pepper shaker.
7. Stick your finger in the pepper-water and see if anything happens to the pepper.
8. Coat another of your fingers with soap, and place the soapy finger in the water.Notice how the pepper reacts.Try to determine why.
9. Break each bar of soap in half, and examine the inside of each bar.Note any differences in appearance and texture.
10. Place each type of soap, one type at a time, on a paper towel, and put the pieces in the microwave on HIGH for about 2 minutes.Observe each soap sample for the whole time, and record all observations.
11. Take a survey to find out which soap brands are most popular and why.
12. If desired, create your own brand of soap, and test it against existing brands (optional).
13. Analyze the data from all of the above procedures.
14. Interpret your results in a detailed report.
15. Illustrate your findings using colorful graphs and charts.
16. Include soap samples in your science fair display.
17. Show interesting photos taken throughout the course of the project

0

Does Aspirin Help Plants Grow?

Plants and aspirin are an unlikely combination, but aspirin does make humans feel better....why not plants? In this experiment, we will find out whether adding dissolved aspirin to plants help it grow healthier and faster.

Problem:

Does aspirin help plants grow?

Materials:

• Aspirin tablets
• A drinking glass
• Hot water
• Room temperature water
• Seeds
• Two plant pots
• Soil with fertilizer
• Sunlight
• Ruler
• Pen and paper for notes

Procedure

1. Label one pot “Aspirin Water” and the other “Plain Water.”
2. Put some soil into the pot and plant the seeds inside. Cover them up.
3. Take them to a location that gets plenty of sunlight- perhaps outside if it is warm or by a window?
4. Put two tablets of aspirin in a drinking glass.
5. Add hot water to the tablets; they should melt and dissolve. If not, then add boiling water. Stir until completely dissolved.
6. Allow the water to cool to room-temperature.
7. Once the water has cooled, water the seeds in the pot labeled “Aspirin Water.” Do not over-water the seeds. Just add enough water until the soil is moist. Do not get the soil soaking wet.
8. Water the seeds in the pot labeled “Plain Water” with plain water. Again, just get the soil moist.
9. You should water the seeds everyday or when the soil feels dry with the designated types of water.
10. Observe the growth of the plants daily. How long did the seeds take to germinate in each pot? If you observe measureable growth, take your ruler and measure the height of the plant.

Sofia PC is currently a college student with a deep interest in science who is aspiring to become a writer. She writes about all sorts of things across all subjects including, but not limited to; science, crafts, and fashion. She hopes to become a good writer so she can share her thoughts and experiences with the world and future generations.

0

Milk Experiment

Objective

In this milk experiment, we will find out whether whole milk spoils at the same rate as two percent and skim milk.

Introduction

When something is spoiled, it is definitely expired; but if something is expired, it doesn't have to be spoiled. Why is that? That's because the expiration date printed on the foods we eat are not always 100 percent set in stone. You should still rely on your senses and good judgment to determine whether something is safe to eat or not.
But when something is spoiled, you can most likely see or at least smell it before finding out the hard way (a.k.a. eating/drinking it and then hugging the toilet for the next few hours). Once something is consumed it is much harder to relieve than a brief nasty scent or an unpleasant sight. Never eat or drink spoiled foods; look and smell it before taking the leap and eating it!

Research Questions

• What happens when food is spoiled?

 

Materials

• Whole vitamin D milk (the milk should have identical expiration dates)
• 2% milk
• Skim milk
• 3 drinking glasses
• Magnifying glass

Terms to Know

• Bacteria
• Germs
• Food spoilage
• Milk content

Experimental Procedure

1. Pour the whole milk, 2% milk, and skim milk in 3 separate glasses. Label each one so you will know what kind of milk in in each.
2. Set these glasses in the open air at room temperature.
3. Observe what happens daily.
4. In about three days, you should notice an unpleasant smell. Observe which glass the smell is coming from.
5. Pour out the milk.

Suggested Chart

	Day 1	Day 2	Day 3	Day 4	Day 5
Whole Milk
2% Milk
Skim Milk

References

• http://en.wikipedia.org/wiki/Bacteria
• http://home.pacific.net.hk/~ppleung/Chem/spoilage.htm

Sofia PC is currently a college student with a deep interest in science who is aspiring to become a writer. She writes about all sorts of things across all subjects including, but not limited to; science, crafts, and fashion. She hopes to become a good writer so she can share her thoughts and experiences with the world and future generations.

0

Dry Ice Effects

Objective:

In this experiment you will become familiar with the properties of dry ice while creating interesting effects.

Research Questions:

• What temperature is dry ice?
• What is dry ice composed of?
• How do you make dry ice?

Most people know dry ice is used for fog at parties or in movie scenes. In this experiment you will become familiar with the properties of dry ice and create interesting effects.

Materials:

• Dry ice
• Water
• Large bowl
• Bubble solution
• Dishwashing liquid
• Plastic water bottle
• Dishrag

Experimental Procedure

• Tiny Bubbles

1. Fill the large bowl with warm water.
2. Pour in some bubble solution.
3. Drop the dry ice into it
4. Watch as it quickly begins to make a countless amount of bubbles.

• Balloon Pop

1. Put a medium sized chunk of dry ice into the plastic bottle.
2. Pour water into the bottle.
3. Quickly put the balloon over the bottle head.
4. Watch as the gas from the dry ice fills the balloon and causes it to pop.

• Big Bubble

1. Fill the large bowl with warm water.
2. Pour in some bubble solution.
3. Drop some dry ice into the bowl.
4. Pour some dishwashing liquid onto the dishrag.
5. Run it under some warm water.
6. Slide the dish rag along the rim of the bowl, covering it with a film of dishwashing liquid.
7. Watch as the gas fills the film and forms one giant bubble.

Terms/Concepts: dry ice, carbon dioxide. elements in all three forms of matter (solid, liquid, gas)

0

Salt Water Energy

Objective:

This science project will explore the components of a battery, specifically how the conductivity of the solution in the battery affects how much electricity it generates.

Research Question:

• How can you make electricity from simple objects around the house?
• How does the amount of salt in a solution affect the solution’s ability to conduct energy?

We use batteries in everything – from IPods to cars. But how does a battery work? In this science project, you will build a battery and see how one of its components contributes to its ability to generate electricity.

Materials:

• Water
• Small glass jar
• Salt
• Measuring spoons
• Zinc-coated nail
• Tape
• Copper-coated wire
• 2 insulated wires with alligator clips on both ends.
• Voltmeter (borrowed)
• Graph paper, optional


Experimental Procedure:

1. Make a saltwater solution by mixing a small jar of water with a teaspoon of salt.
2. Place a zinc-coated nail into the solution, and tape it to one side of the cup securely. This will be the negative electrode.
3. Place a copper-coated wire into the solution, and tape it to the other side of the cup securely. This will be the positive electrode.
4. Open the alligator clip on one wire by squeezing it, and attach it to the end of the zinc-coated wire sticking out of the solution.
5. Open the alligator clip on the other end of the wire, and attach it to the negative pole of the voltmeter.
6. Repeat Steps 4 and 5 to connect the copper-coated nail to the positive pole of the voltmeter.
7. Look at the dial on the voltmeter. How much current does it show flowing between the two electrodes?
8. Add another teaspoon of salt to the water. How much current does the voltmeter show now? Continue adding teaspoons of salt and recording the reading on the voltmeter in a chart, such as the one below.

If you’d like, you can make a line graph showing the relationship between the amount of salt in the water and the current that flows between the two electrodes. Is there a point at which the current stops increasing?
Terms/Concepts:Voltage; How does a voltmeter work?; What are the parts of a battery (e.g., electrodes)?

0

Growing Crystals

The goal of this experiment is to learn about how crystals form.

• What is a crystal? What is the difference between a crystal and glass? Do the molecules in glass form a distinct pattern? What about the molecules in a crystal?
• What conditions are necessary for a molecule to form? Is there anything you can change to make crystals form faster?Does temperature affect how rapidly crystals form?
• Once a crystal has formed, what makes the crystal continue to grow? Do crystals grow from the inside out or from the outside in?

Man has long been fascinated by crystals.Recognizing their beauty, we may wear them as ornaments and purchase crystal-growing kits for our children. Some people even believe that certain types of crystals are associated with particular states of mind.However, some of the best crystals are grown without using store-bought kits.

The molecules in crystals are different from the molecules in other substances because they are aligned in a recognizable, repetitive pattern.This is very different from glass because the molecules in solid glass have the same random pattern that they did when the glass was in a liquid state. This regular alignment occurs when crystals emerge from a supersaturated solution. A super-saturated solution is one that contains more molecules of a dissolved crystalline solid that than the liquid can hold. Since you can dissolve more of a substance in hot water than you can in cold water, a supersaturated state is achieved by dissolving a substance in hot water.As the solution cools, it will hold less of the dissolved substance.As it cools, crystals form.They will continue to grow for as long as there liquid is present.The characteristic shape of a particular type of crystal is called its habit.

• Lab book and pencil (all experiments)
• Water (all experiments)
• Tablespoon (all experiments)
• Small glass bowl (all experiments)
• Thermometer (all experiments)
• Measuring cup (all experiments)
• Charcoal briquettes (experiment #1)
• Salt (experiment #1)
• Ammonia (experiment #1)
• Water (experiment #1)
• Bluing (experiment #1)- Mrs. Stewart’s is best
• Food coloring or colored ink (experiment #1)
• Any of the following: alum, borax, sodium bicarbonate, potassium chromate, potassium dichromate, ferrous sulfate, ammonium chloride (experiment #2, optional)
• Clean jars with screw-on lids (pint-size)
• Small saucers or custard dishes (all experiments)
• Nylon filament fishing line. (experiment #2)

EXPERIMENT #1

1. Place two or three charcoal briquettes in the bottom of the bowl.
2. Mix the following substances together and stir well: ¼ cup water ¼ cup bluing ¼ cup table salt 1 tablespoon ammonia
3. If you wish to make colored crystals place several drops of food coloring or colored ink at various locations on the briquettes.
4. Carefully pour the solution you made in step #2 over the briquettes.
5. Set the dish aside where it will not be disturbed. Examine the dish twice daily. Record the temperature of the air where the dish is located and what you see when you inspect the dish. Continue making observations twice daily until the liquid has evaporated (usually less than one week).

EXPERIMENT #2

1. Boil a gallon of water.
2. Being careful not to burn yourself, measure 1 cup of the water and put it in a pint-size jar.
3. Add level tablespoonfuls of any one of the following chemicals: alum, borax, sodium bicarbonate, potassium chromate, potassium dichromate, ferrous sulfate or ammonium chloride.After each addition, stir until the chemical is dissolved.Keep adding the chemical until no more will dissolve.
4. Pour roughly ¼ cup of the super-saturated solution that you made in step 3 into a small saucer or custard dish and set aside.Cover the jar containing the solution.You will use this solution again in step 6.
5. Inspect the saucer or custard dish twice a day for crystals.When you see a perfectly regular shape of a single crystal, remove the crystal with tweezers or a toothpick.Very carefully, tie one end of a nylon fishing line around the crystal.It helps if you make a loose slip knot that you can loop over the crystal and gently tighten it.
6. Tie the loose end of the fishing line around the middle of a pencil and suspend the crystal into the stock solution that you prepared in step 2.By bathing the individual crystal, it can grow freely. Leave the lid off, but leave the dish in a place where dust will not fall into the jar.
7. Continue inspecting your crystals in the saucer and in the super saturated solution.Document your observations, including the temperature of the air.

Terms/Concepts:Crystals; Super-saturation; Polycrystalline mass; Molecular patterns; Crystal habit; Seed crystal; Crystal growth

0

How to Hollow Out an Egg

The best way to hollow out an egg depends on how you're going to use it. If it's important that the holes be small, you can pierce the egg with a paperclip or push pin and blow out the interior. If the holes can be larger, your task is much easier.

 

Things You'll Need

• Raw eggs
• Pushpin
• Paperclip
• Manicure scissors
• Dish

Small Hole Method

Step 1: Wash the Eggs

Wash the eggs with warm water and mild dish soap. Rinse and dry thoroughly.

 

Step 2: Make Small Holes at Each End of the Egg

Hold the egg over the dish. Pierce the larger end of the egg first with the push pin. You may have to twist the push pin to pierce the shell.
Flip the egg around and make a slightly bigger hole in the opposite smaller end. Continue holding the egg over the dish, as the yolk may leak from the hole.

 

Step 3: Enlarge the Holes

Straighten out a paper clip. Insert the wire into the end of the egg with the larger hole. Move the wire gently around inside the egg to break up the yolk. The goal it to scramble the yolk and white to make it easier to blow them out.

Step 4: Blow Out the Egg

Holding the egg over a bowl, place your mouth over the hole at the small end of the egg and blow until the contents of the egg drain out. Rinse the egg thoroughly until the water runs clear.

Blow into the hole at the small end of the egg.

Step 5: Decorate

Use glitter and Mod Podge to decorate as desired.

Large Hole Method

Step 1: Pierce the Egg with the Scissors

Using the points of sharp manicure scissors, pierce the small end of the egg. Insert the scissors into the hole and snip a hole in the desired size and shape. Shake the contents into a bowl.

Step 2: Wash the Inside of the Shell

Wash out the inside of the egg with warm soapy water. Dry thoroughly. Decorate as desired.

 

0