AP Chemistry
Chemistry Lab: Coffee Cup Calorimetry
Overview:
a physical
reaction that occur in aqueous solution. You will use a styrofoam cup calorimeter and various
reactants according to the instructions below.
Safety: NaOH is a strong base. Goggles are a must and gloves must be worn when measuring
out NaOH (s).
Procedures:
1. Obtain a Styrofoam calorimeter and a plastic lid. The hole is so that you can put a
thermometer through.
2. Obtain a digital thermometer.
3. Measure out 40 ml of distilled water into the styrofoam cup. Record the mass of the water
(remember to tare for the mass of the cup). Measure the temperature of the water.
4. Place the cup in a 400 mL beaker to secure it during your reactions.
5. Weigh out about 2 grams of solid NaOH. Record the exact weight.
6. Dump the solid NaOH into the styrofoam cup and swirl to dissolve the salt. Keep the lid on
the calorimeter as much as possible and record the increase in temperature. You will have to
judge when the dissolution reaction is complete.
7. Calculate the number of Joules that were released in this exothermic process using the
following calculation for the specific heat of water: q = s x m x ΔT
s (specific heat capacity) = 4.18 J/g K (specifically for water)
m = mass of H2O,
ΔT = change in temp (K)
8. Try to come up with a value of kJ/mole for this reaction:
NaOH(s)  NaOH (aq) (“ideal” ΔH = -44.51 kJ/mol)
Trial #
Trial 1
Trial 2
Mass of Water
Mass of NaOH
Initial Temp (°C)
Final Temp (˚C)
Questions for Coffee Cup Calorimetry Lab
1. Compare your results (kJ/Mol) to the ideal value given. What is your present error? Try
to give three reasons why your number (kJ/mol) may be different from the ideal value.
Do not resort to "human error"--try to be more specific and more insightful.
2. Show your method for calculating the kJ/mole for the reaction you ran. Explain each step
as if you were tutoring someone who was absent this week.
3. Why is it important that these reactions be run in a styrofoam cup (as opposed to a
beaker)?
4. Is it possible to measure the temperature of a solution without changing the
temperature? That is, does the presence of the measuring device (thermometer) affect the
reading?
5. The reaction done in this lab was exothermic. Do you think it would be possible to use a
coffee cup and a thermometer to measure the ΔH value of an endothermic reaction?
Explain.
Lab Write-up:
1. Data table
2. Results table, including % error
3. Answer to post-lab questions
4. Conclusion (summary paragraph)