Name _______________________
Date _______
Period 1 2 3 4 5 6
Regular Chemistry Spring Performance Task
Practice
A calorimetry experiment is carried out to determine the heat of solution for potassium
chloride. In a typical experiment, 100 mL of water at 25.0 °C is placed in the polystyrene cup
and the initial temperature of the water recorded. 5.05 g potassium chloride, KCl, is added to
the water while stirring. The temperature of the solution falls and the minimum temperature
achieved is recorded as 21.7 °C.
Data Table
VH2O
MKCl
Tinitial
Tfinal
Cwater
=
=
=
=
=
volume of water
mass of KCl(s)
initial temperature
final temperature
Specific heat water
=
=
=
=
=
1. Fill in the data table above
2. Write a balanced equation for the dissolution of
potassium chloride
3. Draw a picture or use a paragraph to describe the interaction between the water
molecules and ions after being fully dissolved.
4. What is the mass of the solution?
5. Calculate T for the solution
6. Assuming the polystyrene foam cup is well insulated and the specific heat capacity of water
is 4.18 J/goC , determine the heat of solution of sodium hydroxide.
7. Is this reaction endothermic or exothermic? How do you know this? Reference data from
lab to back up your claim.
8. A student places two 10.0 g samples of metal, at 25oC each, are exposed to 20 J of heat.
One sample is Lead (CPb = 0.129 J/gC) and the other is silver (CAg= 0.235 J/gC).
a. Which one will have a higher final temperature? __________________________
b. Explain your choice *hint* no math is required for this one:
9. Two samples of copper (50 gram and 25 gram) are exposed to 10 J of heat energy. Both
started at 10oC. The specific heat of copper is 0.385 J/gC.
a. Which will have a higher final temperature? __________________________
b. Explain your choice *hint* no math is required for this one:
10. A calorimetry experiment is carried out to determine the identity of an unknown
metal. A 25.6 g piece of metal was taken from a beaker of boiling water at 100.0 °C and placed
directly into a calorimeter holding 100.0 mL of water at 25.0 °C. Given that the final
temperature at thermal equilibrium is 26.2 °C, determine the specific heat capacity of the
metal.
1) Determine the mass of the water
2) Determine the energy lost by the water
3) Determine the energy gained by the metal
4) Determine the heat capacity of the metal
4) Identify the metal using the list of specific heats found at the link below:
http://www.engineeringtoolbox.com/specific-heat-metals-d_152.html
5) Write a paragraph to describe how the Law of Conservation of Energy applies to calorimetry.
This should also explain how we were able to get our answer for #3 of this problem.