Bonus Take Home Lab #2

Take Home Lab Bonus #2:  Penny Sandwiches

Question: From 1864 until 1983, the usual composition of a penny (its actual name is “cent”) was 95% copper and 5% zinc and tin. Because of the increasing costs of copper, pennies are now composed of a zinc interior with a thin copper coating comprising only 2.4% of the penny. This activity allows you to remove the inside of the penny, leaving only the thin copper coating.

Safety: Do not seal the bottles. The pressure of the hydrogen gas may be sufficient to shatter the bottles.

Materials: 2 pennies (dated 1983 or later), a file or coarse sandpaper, 2 cups lemon juice, 2 cups vinegar, 2 clear wide-mouthed containers (greater than 2 cup measurement)

Procedure:

STEP 1:  Using the file or coarse sandpaper, completely remove the copper coating from the edge of both pennies. Pour the lemon juice into one container. Position one penny in the container so that it is standing on its edge against the side of the container. Pour the vinegar into the second container and similarly position the second penny. Observe the pennies for 4 or 5 minutes. What do you see? What is occurring? What is the identity of the observed substance?

STEP 2: Observe the pennies over the course of 1 week and describe any difference(s) in their behavior. What accounts for the difference(s)? What specific process is occurring in each container? How do you know when the processes are complete? Use your observations to rank the three elements hydrogen, copper, and zinc from most to least reactive.

Observations:

Step 1:  Penny in container of lemon juice—

 Penny in container of vinegar—

Step 2:  Penny in lemon juice after 1 week—

                Penny in vinegar after 1 week—

               

Post-Lab Questions:

1. What gas do you think is being released by the pennies?

2. Was there a difference between the container of vinegar and lemon juice? Why do you think there was a difference if there was one?

3.  Rank these from the most to the least reactive. Copper, zinc and hydrogen.

4. What do you think is more reactive lemon juice or vinegar? Explain from your observations.

5. Why do you think they place a copper coating on the penny?

Bonus Take Home Lab #1

Take Home Lab Bonus #1:  Tissue in a Cup: How Soggy?

Question: Have you washed any cups or glasses recently? Have you ever tried to submerge an inverted glass, jar, or cup into water only to have it bob back to the surface without the inside getting wet? What does this have to do with chemistry? You will find out as you investigate several aspects of this phenomenon through this activity.

Safety: Clean up any spills immediately, be careful of push pin and nail

Materials: clear glass or plastic cup, paper cup, tissues or paper towels, push pin or nail, ice cold water, very hot tap water, 2 containers to completely submerge the cups (preferably clear)

Procedure:

STEP 1:  Fill one large container with ice-cold water. Fill the second large container with very hot tap water. Submerge an inverted clear cup or glass in the cold water for several minutes and observe from the side. Remove the cup from the cold water and, taking care not to burn yourself, submerge the inverted cup in the hot water for several minutes and observe as before. Repeat the submersion in cold and then hot water. Record your observations. Explain any differences in your observations of the cup in cold and hot water. Draw a picture to show the difference between the hot and cold water.

STEP 2: Using any of the materials listed above, devise a way to submerge a tissue or paper towel under water without getting it wet. Briefly outline your procedure and draw a labeled picture to illustrate what you observed. What kept your tissue from becoming wet?

STEP 3: Using any of the materials listed above, devise a way to submerge a tissue or paper towel under water without getting it wet. Briefly outline your procedure and draw a labeled picture to illustrate what you observed. What kept your tissue from becoming wet?

Observations:

Step 1:  Cold water container—

 Hot water container—

Step 2:  Tissue in the cup—

Step 3:  Paper cup with hole--

               

Diagrams w/ labels explaining the parts:

Step 1:

Step 2:

Step 3:

Post-Lab Questions:

1. What happened to the air in the submerged cups?

2. How was the hot water result different from the cold water? Why do you think this is?

3.  Did your tissue paper get wet? Why or why not?

4. What did you do right, what did you do wrong?

Take Home Lab #6

Take Home Lab #6:  Measure a Meltdown

Question: What will happen to the Earth’s oceans if the ice melts in places such as Antarctica and Greenland? Does melting icebergs cause sea level change?

Safety: Clean up any spills immediately.

Materials: clear glass or clear plastic bowl about 6 in/15 cm in diameter, ice cubes, warm water, pencil/marker, ruler

Procedure:

Trial #1:

1. Pour warm water so that the level of the liquid is roughly 2.5 centimeters (1 inch) from the top of the bowl.

2. Place 4-5 ice cubes in the bowl.

3. Use a water-based marker (one that will wipe off easily!) to draw a line on the outside of the container at the level of the water after you placed the ice cubes.

4. Set the bowl aside for 15 minutes, or until all of the ice melts.

5. Mark the new level of the water. Then use a ruler to measure how much the level changed.

Trial #2:

1.  Think about whether your experiment in Trial #1 represents melting icebergs (ice that is already floating in the sea) or glaciers (huge ice sheets on land such as Antarctica and Greenland).

2. How could you modify your experiment so that it models how melting glaciers would affect sea level.

3. Repeat your experiment with your new set up.

Data Table:

	Initial height: (Describe the height of your ice cubes and water before_	Final height: (Describe the height of your ice cubes and water after)
Trial #1: ice cubes in water
Trial #2: your design

               

Post-Lab Questions:

1. Explain does Trial #1 represent melting icebergs or melting glaciers? Explain which it shows and why.

2. Explain how you conducted your experiment in Trial #2. Explain your set up.

3. Did the water levels in your trails rise or fall when the ice melted? Explain how Trial #1 was different or the same from Trial #2. 

4. In which setup did the water level change the most? By how much?

5. Which melting ice will have the largest impact on sea levels: icebergs or glaciers? Support your answer with evidence from your experiment.

Take Home Lab #5

Take Home Lab #5:  Dissolving Energy

Question: When you dissolve household chemicals is it exothermic or endothermic?

Safety: Clean up any spills immediately. Do not consume any of the chemicals. Wash out cups well after mixing chemicals.

Materials: Cup, room temperature water, salt, borax, powdered “ultra” laundry detergent, baking soda, thermometer

Procedure: In this investigation, you are going to dissolve different common household chemicals to see if these reactions are exothermic or endothermic changes.

1. Pour ¼ cup of water in a cup. Measure the initial temperature and record in your data table.

2. Add 2 tablespoons of baking soda to the water. Mix to dissolve and find the new temperature and record in your data table.

3. Wash out the cup and start step #1 again with a clean cup of water. Record the temperature

4. Add 2 tablespoons of salt to the water and stir to dissolve, measure the temperature and record to data table.

5. Repeat these steps with “ultra” powder laundry detergent and borax.

Data Table:

Substance:	Initial temperature of water:	Final temperature of mixture:
Baking soda
Salt
“Ultra” Laundry
Borax

               

Post-Lab Questions:

1. Identify which of the experiments were exothermic and endothermic.

2. What is your evidence that the reactions were exothermic and endothermic, how do you know?

3. Make two models to show what occurred in the exothermic reaction and endothermic reaction.

4. Calculate the amount of energy released or absorbed when water and baking soda were mixed. Use the formula Q=s∙m∙DT. (Where the mass of the water is 30g, s for water is 4.18 J/g∙C and your information from your data table.

5. Calculate the amount of energy released or absorbed when water and laundry detergent were mixed. Use the same formula and information from the question above.

Take Home Lab #4

Take Home Lab #4:  Finger Thermometer

Question: Can your finger be used as an accurate thermometer?

Safety: Only warm water and refrigerator-cold water should be used for this activity. If the activity becomes uncomfortable at any time, stop immediately. Clean up any spills to prevent slipping and falling.

Materials: 3 cups with cold water, room temperature water, and warm water

Procedure: You can put your finger in a cup of water and determine if it is hot or cold. But how accurate is your finger as a thermometer? In this activity, you will find out if your finger is more of a temperature detector or a detector of changes in temperature.

1. Get three drinking cups ready with a wide enough mouth that allows you to put your finger in the water.

2. In the left cup, put cold water either from the refrigerator or tap water with a couple of ice cubes in it. In the middle cup, put room-temperature tap water. In the right cup, put warm tap water.

3. Put a finger from your left hand in the left (cold) cup and put your right finger in the right (warm) cup of water. Wait 30 seconds, then put both fingers in the middle cup. Think about how the water feels to each of the fingers.

Post-Lab Questions:

1. How did the water feel to your left hand? How did the water feel to your right hand?

2. Is your skin a temperature detector or a change-in-temperature detector?

3. How is this similar to the optical illusions where you stare at a colored object for 30 seconds and then stare at a blank wall? If you have not seen on of these before, use your favorite online search engine to search for “American Flag Optical Illusion.”

Part 2:

Procedure:

Find a smooth object (such a sheet protector, plastic cover of a composition book, or other smooth piece of plastic) and a sheet of paper. Set the smooth object near carpet. For 30 seconds, rub the fingers of your left hand on the carpet and the fingers of your right hand on the smooth object. After 30 seconds, rub the fingers of both hands on the sheet of paper.

Post-Lab Questions:

1. How does the paper feel to your left hand? How does it feel to your right hand?

2. How is this similar to the finger thermometer?

Take Home Lab #3

Take Home Lab #3:  Half-Life Simulation

Question: What is the half-life of a simulated nuclear reaction?

Safety: Be careful with the scissors and keep them out of the reach of small children.

Materials: copy of provided paper, scissors, a box

Procedure: In this lab, you will simulate the graphing of the half-life of a radioactive substance using slips of paper. A half-life is defined as the time that it takes for half of a radioactive material to decay into another substance. You will simulate this process by flipping some papers and taking out all that are facing the same direction and continuing. The papers with the symbol facing down represent atoms that are radioactive. Those facing up have already decayed.

                Cut out all the pieces of paper with the Greek letter a (Alpha) on them. Put them in a box and shake them up. Take out all the pieces that have the a facing up. Count and record how many are left. Shake the box again, and again remove all of the pieces that have the a facing up. Count and record how many are left. Continue this until no pieces are left. Repeat this procedure one more time.

Data Table:

Trial number:	Number of papers left:
1	100
2
3
4
5
6
7

Prepare a graph with trial # on the x-axis and the number of papers left on the y-axis.

 

Papers

left

 

                                                Trial #

Post-Lab Questions:

1. How many shakes did it take to get rid of all the papers?

2. Use your graph to interpolate the half-life if each shake represents 1,000 years.

3. Use your graph to answer the question, “How many years have passed when 25% of the papers are left?”

4. According to your data, what is the oldest object that this method could be used to date?

Take Home Lab #2

Take Home Lab #2:  Invisible Ink

Question: What chemical makes invisible ink work?

Safety: Do not eat or drink any of the materials. Clean up any spills.

Materials: Students determine what materials to use.

Procedure: One way to make an invisible ink is to write on a piece of paper with the juice from a fruit and let it dry. Then heating it above a toaster or with a hair dryer will make the writing visible. But what chemical in the fruit juice makes the color change? This is what you will attempt to figure out in this activity.

                First, make sure that you can do the demonstration with a liquid known to work. Use a stick or a cotton swab to write something on a piece of scratch paper (do not waste a new piece of paper) with lemon, apple or pineapple juice. If the juice does not come straight from the fruit, be sure to make sure there is real fruit juice in it. Many fruit drinks that you buy in the store do not really have any fruit juice in them.

                Allow the juice to dry until it is invisible. Hold the paper 2 inches above a toaster (holding the edges of the paper so you do not burn yourself, hold it over a lightbulb, or put it 2 inches in front of a hair dryer. Watch for a couple of minutes to see if the invisible ink becomes visible. If it does not, keep trying until you can see it before you start your investigation.

                Now that you can get invisible ink to turn visible, you will try to figure out what is in the liquid you used that made the ink show up when heated. When you have a hypothesis for what chemical it might be, make up a solution of that chemical and test it. For example, if you believe that salt is what turns colors, test some salt water using the same procedure you did for the fruit juice. Try testing other liquids that have similar chemical and different chemicals.

                Keep a list of the liquids that you tested and a description of the results similar to the chart below.  You must test at least four different liquids.

Data Table:

Liquid:	Observations:
Fruit Juice

Post-Lab Questions:

1. Which liquids made successful invisible inks? Which liquids did not?

2. What did the successful liquids all have in them that the unsuccessful liquids did not?

3. What did your experiments tell you is in the fruit juice that makes it a good invisible ink? Explain your thought process as you came to this conclusion. Use statements such as “ Because _____ and _____ happened, I eliminated ________. Because _____ and ______ were successful, I decided to test _____. And because _____ happened, I conclude that the chemical that makes fruit juice work as an invisible ink is _____.”

Take Home Lab #1 spring semester

Take Home Lab #1:  Growing Crystals

Question: How are crystals of different crystals similar and different?

Safety: Do not eat any of the crystals or other materials during this activity, as mold quickly grows on some of the crystals. Mark the cups clearly and keep them out of the reach of children .Clean up spills immediately.

Materials: cups, water, sugar, salt, Epsom salt, thread

Procedure: In this lab, you will grow three different types of crystals: sugar, salt and Epsom salts. Crystals are grown by either dissolving more material than the solvent (the water) can normally hold by heating it, or by allowing the solvent to evaporate over time. In this procedure, you will do a little of both. You will put a lot of solute (the substance that dissolves) in a little solvent and heat it to dissolve; then you will let it sit for a few days to evaporate.

1. For each of the solutes (salt, sugar, Epsom salts), dissolve a large spoonful in 1 cup of boiling water in a glass cup.  (Be careful when boiling water please!) For sugar you will need to add 2-3 large spoonfuls of sugar to 1 cup of boiling water. Stir until all of the solute is gone.

2. Tie a paperclip to the end of a short thread and tie to a pencil or pen to hang in the water with the dissolved solute.  Allow it to sit on a windowsill for several days while the water evaporates. Pull the string out and let the crystals dry overnight.  Record observations of your crystals every day and include the number of crystals, size, shape and other characteristics.

3. Find a good example of each crystal and sketch its shape. Try to find a single crystal without other crystals growing out of it.

Post-Lab Questions:

1. Make a daily log for 5 days of your crystals.  Make a sketch for each(sugar, salt, Epsom salts) one during these 5 days.  Note the number and shape in your drawings. Make it as accurate looking as possible.

2. Which substance grew the largest crystals?

3. How would you describe the shape of each crystal? Describe all three and they will have different shapes!

4. You used three different chemicals to grow these crystals: salt (NaCl), sugar (C₁₂H₂₂O₁₁) and Epsom salts (MgSO₄).  Which of these molecules is the largest (hint: look at their chemical formula)? Did that substance grow the largest crystals? Did the chemical with the smallest molecule grow the smallest crystals? Explain.