Mr. O
Name:
Lab 18
Title: Calorimerty: Heat of Crystallization of Wax
Objective: Find the heat of fusion of wax
Discussion:
The process of crystallization (solidification) is the exact opposite of the process of fusion (melting).
When a substance undergoes a phase change from liquid to solid, the substance releases heat energy.
Crystallization is an exothermic reaction.
Equipment: beaker 250mL, burner, graduated cylinder 100 mL, thermometer, Ring stand, test tube
holder, wire gauze, Styrofoam cup, and safety goggles
Materials: 10.0gram sample of wax
Procedure: Detailed account
Observation and Data:
Mass of water (m1) in the calorimeter: ____________
Mass of wax sample (m2): __________
T1 =_______
T2=_______
Specific heat capacity of water (c) = 4.18 J/g-OC
Calculations:
1. Find the change in the temperature of the water. (
2. Find the heat gained by the water. ( Q=M1x
T = T2 – T1)
T x C)
3. Find the heat of crystallization of the wax (Q/m2)
Conclusion and Questions:
1. Define the term heat of crystallization. What units could be used to express this
property?
2. During a phase change, what is the potential energy being used for?
3. How does the heat of fusion of a substance compare with the heat of
crystallization of the same substance?
4. Why is the amount of energy in the experiment invalid? How would a
calorimeter decrease error?
5. Explain why this experiment could not be conducted using a mixture?
6. What is the heat of fusion of 12 g sample of a substance which produces 2100
joules of heat?
7. How much energy is produced when 11 grams of water vaporizes?