Station #2 – Thermodynamics
of Cannon Balls
In your lab book:
A. Describe what you think happens when something is smashed.
B. Write a sentence about how energy is transferred.
Let’s try it!
1. Observe a piece of computer paper.
2. Firmly grasp a cannon ball in each hand. -- Be careful to make sure your fingers are out of the
way!!!
3. Smash a piece of paper (like you mean it) between the two cannon balls.
4. Re-examine the computer paper (including odor).
5. Shift the paper to a new spot and repeat to see if you get the same results.
In your lab book:
 What do you notice that is different about the paper after it was smashed between the cannon
balls?
 Draw a cartoon showing the types of energies and transfers involved in this demonstration.
(Hint: What type of energy was involved when the cannonballs were moving? Where did that
energy go then the cannon balls smashed?
Let’s try something different!
1. Now wrap a piece of Aluminum Foil around one ball. Rotate the cannon ball and put the piece
of aluminum on a different spot and try.
2. Firmly grasp a cannon ball in each hand. -- Be careful to make sure your fingers are out of the
way!!!
3. Smash a piece of paper (like you mean it) between the two cannon balls.
4. Re-examine the computer paper (including odor).
5. Remove the paper and smash the piece of aluminum between the two cannon balls. What do
you notice?
In your lab book:
 Describe what you saw, heard, and smelled.
 Is this the same or different than what happened before? (create a T chart to compare and
contrast before and after adding the aluminum foil.)
 Which released/absorbed more energy? Support your answer with evidence.
 Propose an explanation for your answer to the question above. (Hint: look up the thermite
reaction in Google)
Station #1 – Hydration
of a compound
A couple of labs ago, you removed water from a hydrated crystal. The result was a anhydrous (or
partially anhydrous) copper(II) sulfate.
In your lab book:
A. How did you remove the water? Was this process endothermic or exothermic to the
compound? (draw a diagram that shows the flow of energy to support your answer).
B. Predict what would happen if you added water back to the anhydrous Copper(II) sulfate.
Let’s find out!
Caution: Copper(II) sulfate is a respiratory irritant and toxic by ingestion.
Do not breathe vapors or dust
1. Place about 2.0 grams of anhydrous copper(II) sulfate in a 50mL beaker. Record this mass in
your lab book.
2. Gently shake the beaker to evenly spread the powder across the bottom of the beaker
3. Take the temperature of the beaker of distilled water using the temperature probe and record
in your lab book.
4. Use the pipet labeled H2O to add 5 bulbs of water to the anhydrous copper(II) sulfate
5. Observe the effects of hydration on anhydrous copper(II) sulfate.
6. Record observations in your lab book. (note changes in color, temperature, but do not smell!)
7. Use the temperature probe to find the final temperature that the re-hydrated mixture reaches.
8. Transfer the hydrated compound in to the waste container, and rinse and dry the beaker.
In your lab book:
A. Was your prediction supported or not supported by the experiment.
B. Draw a diagram showing the direction of the energy as the water was heated.
C. What temperature do you think would be reached if you used 24.5 grams of anhydrous
copper(II) sulfate and water? Fully explain how you reached this number?
D. Propose an explanation for why adding water causes this change. Use evidence to support
your idea.
Station #3 – What do you
mean it freezes…
Freezing… melting… oh my!
In your lab book:
A. Write a 3 sentence explanation of the difference between temperature and heat.
B. Draw a detailed diagram of the molecules of a liquid as it freezes into a solid. Indicate the
energies of the molecules in your drawing (using arrows of relative size to show motion), and
write a 3 sentence explanation of what is happening to the average kinetic energy of the
molecules as it freezes.
Let’s do Science!
1. Grasp the package of liquid and find the mass of the package.
2. Note the temperature with the supplied temperature probe
3. Use both hands to pinch and bend the little metal disk inside. (It should bend with a little
‘pop’)
4. Observe what happens and record in detail your observations.
5. Measure the temperature once it remains constant for 30 seconds or more.
6. When finished, place the packet into boiling water for 10 minutes. (remove using the crucible
tongs)
In your lab book:
A. Draw a detailed diagram of what you observed during this experiment. Be detailed! How did it
look during the experiment? Where did it start? What did you notice?
B. Use arrows to indicate the direction of energy as this process occurred. Does this support
your drawing you did initially? If you need to revise your drawing, what would change?
C. Is freezing an exothermic or endothermic process? Use data to support your answer.
D. Calculate the temperature change that you would expect if the package had a mass of 1.4
kilograms. Give a detailed, bulleted list of the steps you took to find your answer.
E. Draw a 3 panel cartoon of the freezing and melting of the chemical in the packet. Describe or
illustrate where the energy comes from during the freezing process, and how it is replenished
during the melting process.
F. Come up with a list of uses for the freezing of this chemical.
Station #4
Assaulting fruit
Background: Citric Acid is a weak acid that is the tart tang of lemons, limes, oranges and tangerines. This
Acid gives off a H+ ion, which can be absorbed by another molecule such as baking soda or sodium hydroxide. The
result is the formation of water and an ionic compound called a salt.
In your lab book:
A. Use the side of the container to write the formula for Citric Acid. What is the formula of the citrate ion
after 3H+ ions are released from Citric Acid?
B. Write the balanced equation for the neutralization of Citric Acid and sodium bicarbonate to form
sodium citrate, water, and carbon dioxide.
C. Predict whether this process will absorb or release energy and explain your reasoning.
Let’s Try It!
1. Measure 2.0 grams of sodium bicarbonate and add to a 50mL beaker
2. Measure 2.0 grams of Citric Acid and add to the same 50mL beaker
3. Use the temperature probe to stir the powders and take the temperature of the mix – record in lab
book.
4. Now add 15 mL of water to the beaker and stir with the temperature probe.
5. Be sure to keep your hands away from the sides of the beaker while stirring – you don’t want to
tamper with the energy of the reaction.
6. Record the ending temperature of the mixture in your lab book.
7. When finished, the solution can be washed out of the beaker with soap and water.
In you lab book:
D. Is your prediction supported by the experiment? (Use data to back up your statement)
E. Identify the limiting reactant in the experiment. Justify your answer with calculations.
F. Predict what the temperature would be if 1.5 grams of citric acid was reacted with 2.5 grams of
sodium bicarbonate. (Create a bullet pointed list of the steps you took to arrive at your answer. )
Let’s Try it!
8.
9.
10.
11.
Measure 1.5 grams of citric acid and add to clean dry 50mL beaker
Measure 2.5 grams of citric acid and add to the same beaker
Add 15 mL of water and stir with the temperature probe.
Record the final temperature of the solution.
In your lab book:
G. Was your prediction supported by your experiment?
H. What was your % error?
I. Describe factors that would cause error in this lab, and explain how these error would make the
calculated ΔH too high or too low.
Station #5
All about that base…
Background:
Hydrochloric acid is the strongest acid commercially available. This means that HCl completely breaks
apart into H+ ions and Cl- ions when in water. This makes it very easy to react with bases such as NaOH to form water and a
salt.
Molarity refers to how many moles of substance are in a liter of the solution. The solution is usually
contains just water, but it also applies to other solvents as well. For example, a 1M NaCL solution (read 1 molar sodium
chloride solution) would have 1 mole NaCl dissolved in water to make 1Liter. You can think of molarity as a unit conversion
from moles to liters!
In your lab book:
A. Write the balanced equation for the reaction of sodium hydroxide and hydrochloric acid, and state
what type of reaction this is. (Combustion, synthesis, decomposition, etc)
B. Calculate the number of moles of NaOH there are in 200mL of 1M. Show your work.
C. Write a three sentence explanation of acid base neutralization, and draw a 3 panel cartoon to illustrate
your explanation.
D. Predict the direction of energy flow (ΔH) as the neutralization of HCl with NaOH occurs.
Let’s Do Science!
2 M Hydrochloric acid is concentrated and can irreparable damage eyes and skin. 1M NaOH can
cause permanent damage to eyes. Wear safety goggles and take use caution when handling.
1. Use the bottle labeled “Distilled Water” and the graduated cylinder to determine how many drops it
takes to make exactly 2 mL of volume. Record this as a conversion in your lab notebook.
2. Use the temperature probe to determine the temperature of the room. This will serve as the
temperature for the acid and base before adding them together. Record this temperature in your lab
book.
3. Add 40 drops of 1M NaOH to the test tube.
4. Add 20 drops of 2M HCl to the test tube.
5. Use the temperature probe to mix the chemicals and note the end temperature when it stays constant
for 30 seconds or more.
6. Dispose of the mixture down the drain and rinse well with water. Dry off the test tube and return to it
to the rack.
In your lab book:
E. Is your prediction supported or not supported? Use data to justify your answer.
F. Draw an energy diagram for this reaction.
G. The specific heat of water is 4.184J/goC. Calculate the number of joules that were involved in this
reaction.
H. Use the conversion you recorded in step #1 to calculate the number of mL of HCl you used in this
experiment.
I. Calculate the number of moles of HCl you used in this experiment.
J. Calculate the energy of the reaction (ΔH) using the answer from analysis part G and I. Express your
answer in joules/mole.
K. Write a balanced thermochemical equation for the neutralization of Hydrochloric Acid with Sodium
Hydroxide. Be sure to express the correct sign on ΔH.
Station #6
A solution for your dilution
Background:
Dilution is the process of giving something more space to move around in.
In your lab book:
A. Predict what affect adding water to acid would have. Use a picture to illustrate your answer.
B. Molarity is calculated as moles/ liters. If you have 2.4 moles of HCl in 500ml, what is your molarity?
C. If 4.0 mL of 2M HCl solution are added to 10 mL of water, did the number of moles of HCl change?
Justify your answer with a calculation.
D. Create a bulleted list of the steps you would need to solve for the new molarity in part C.
E. Calculate the new molarity in part C.
Let’s try it.
Caution: Concentrated acid can cause irreparable damage to your eyes.
Wear goggles. Always add acid to water, not the other way around.
1. Measure 3 mL of water and place in a test tube.
2. Use the temperature probe to get an initial temperature of the water – record in your lab book.
3. Add 3 mL of 2.0 M HCl to the test tube using the pipette labeled HCl. Look closely at the solution as
you add the acid to the water.
Make sure to replace the pipette on the bottle of acid… don’t lay it on the counter
4. Use the temperature probe to check for a temperature change. If one occurs, wait until it stabilizes for
20 seconds then record.
5. Fill the waste beaker with 10 mL of water.
6. Add 3 drops of Universal Indicator.
7. Pour contents of test tube into waste container.
8. Add small amounts of ‘neutralizer’ until the solution turns green or blue/purple.
9. Stir with glass stir rod to ensure it is well mixed.
10. Dispose of waste down the drain with lots of water.
In your lab book:
F.
G.
H.
I.
J.
Was energy transferred in this activity? If so, what direction? Use data as evidence for your claim.
Calculate the amount of energy that was transferred during the dilution.
Calculate the number of moles of HCl that you used.
Calcualte the heat of dilution (ΔHdil) and express your answer in joules / moles. (Hint: Divide the
energy you found in part G by the moles you found in part H. )
Draw a 2 panel cartoon diagram of the interactions of water molecules, H+ ions, and Cl- ions to
propose an explanation of why the dilution affected the energy. (Hint: read the back side of the card
attached to this page!)
Why does mixing a strong acid with water
release so much heat?
Breaking a chemical bond requires energy (just as stretching a spring until it breaks requires energy).
Forming a chemical bond will release energy. So in a reaction that releases heat (called an exothermic
reaction), there must be net bond formation. If you look at the equation for dissolving a strong acid like HCl in
water,
H2O
HCl(concentrated)
H+ (aq) + Cl-(aq)
you might think at first that this would have to be a heat-absorbing (endothermic) process, because it looks
like the bond between H and Cl is broken. But there is another reaction hiding here. The hydrogen ion reacts
with water to form a complex of the form H3O•(H2O)+n (where the n can vary a bit). Whenever we write
H+(aq), we actually mean H3O•(H2O)+n. (It's much easier to write H+(aq)!) Because the hydrogen ion is so
tiny, a large amount of charge is concentrated in a very small area, and the polar water molecules are
strongly attracted to it. This 'hydration' of the hydrogen ion involves the formation of a covalent bond to one
of the waters and a large number of strong hydrogen bonds, so it's a strongly exothermic process. This
causes the mixing of a strong acid with water to be strongly exothermic overall.
Station #7
The electrocution of water
Background:
It’s been said that water is a poor conductor of electricity… and it is TRUE! These guys however
have no understanding of the chemistry behind that statement. Not only are they as sharp as a ball… they have
absolutely no idea as to what electricity is. I don’t care what size of flip flops you wear, don’t ever do this!!!! They
might as well use binoculars to stare at the sun.
In your lab book:
A. Without using Google, write a 3-sentence explanation of what electricity is (don’t just say energy).
B. Electricity moves very well through metals, but poorly through rubber and other molecular
compounds. Draw a diagram of how a metallic bond works, and compare that to a drawing of how a
molecular (covalent) bond works.
Let’s Investigate:
1.
2.
3.
4.
Examine the water electrolysis apparatus. (Caution: do not touch the wires, you could be shocked!)
Record your observations in your lab book.
Sketch the setup in your lab book, and try to identify the gases that are created.
Adjust the voltage using the nob on the power source. Record any changes into your lab book.
In your lab book:
C. On a Duracell battery, there is a positive side and a negative side. Which side do you think is positive
here? Use evidence to support your claim.
D. What purpose does the electricity serve in this apparatus?
E. Draw a detailed picture showing a molecule of water and what the electricity is doing to the water.
F. What purpose do you think that the sodium sulfate has in this experiment?
G. Predict what would happen if just pure (distilled or deionized water ) was used instead.
H. Is the lysis of water an exothermic or endothermic process? Justify your answer.
Let’s investigate again:
5. Use the provided test tube to collect a little of the gas.
6. Fill the test tube with water from the trough. Keep the mouth of the test tube underwater so the test
tube is pointing down, and trap some bubbles of the gas from the machine. Continue until the test tube
is completely full of gas.
7. Slowly bring the test out of the water, keeping the opening face down.
8. Blow out the stick and quickly (while the stick is glowing) bring it to the opening of the test tube.
In your lab book:
What happened when you put the burning stick to the mouth of each test tube?
Background: Energy flow happens all around us. Just like water, energy always flows downhill –
that is, energy always flows from high to low.
Let’s Play with it!
Black blocks
1.
2.
3.
4.
5.
6.
Notice the black blocks at the station. (Describe them in your lab book)
Touch the bocks. Describe the temperature of each (in your lab book).
Make a prediction – If ice were placed on the two blocks, which one would melt the ice the fastest?
Now put the rubber o-rings on the block.
Put a piece of ice in the middle.
Describe what you see in your lab book.
Analyze it! – In your lab book
A. Did your prediction match your data?
B. Why was one block was able to melt the ice faster than the other. Draw a diagram of the energy flow in
each situation to explain your answer.
Hand Boilers
1. Look at the glass globes connected by a glass tube.
2. Hold one end in a closed fist (don’t squeeze too tightly).
3. Make a prediction, if you and a partner both hold one end, what will happen?
Analyze it! – In your lab book
A. Draw a diagram of the hand boiler showing how energy is flowing in the apparatus.
B. If energy is flowing, where is it being absorbed? Support your answer with evidence.
Bouncy Balls
1. Predict what will happen when you drop the bouncy balls on the floor.
2. Drop the bouncy balls on the floor.
3. Examine the composition of the bouncy balls (without destroying them) – what do you notice?
Analyze it! – In your lab book
A. Draw a diagram of each ball, and explain the energy transfer in each case.
Lava Lamps
A. Draw a detailed diagram of how a lava lamp works. Use arrows to diagram the flow of energy.
B. Predict what would happen if a lava lamp was left on for 8 hours… Use evidence to support your
reasoning.