Lab 5

Latent Heat and Specific Heat

Pre-Lab Questions

1. Water and steam are both 100 ºC when water is boiling, but a burn from steam is worse than a burn from the water. Hypothesize why this is true.

2. A 10 g ice cube, initially at 0 ºC, is melted in 100 g of water that was initially 20 ºC. After the ice has melted, the equilibrium temperature is 10.93 ºC. Calculate:

a. The total heat lost by the water (the specific heat for water is 4.186 J/g/K).

b. The heat gained by the ice cube after it melts (the specific heat for ice is 2.093 J/g/K).

c. The heat it took to melt the ice (Hint: it takes 334 J of heat energy to melt 1 g of ice)

3. Inside a calorimeter is 100 g of water at 39.8 ºC. A 10 g object at 50 ºC is placed inside of a calorimeter. When equilibrium has been reached the new temperature of the water and metal object is 40 ºC. What type of metal is the object made from?

Experiment 1: Latent Heat

Data Sheet

Table 2. Temperature of Frozen Water over Time

Time (s)	Temperature (°C)	Observation
0
5
10
15
20
25
30

Table 3: Temperature of Boiling Water over Time

Time (min.)	Boiling Temperature (°C)
1
5

Post-Lab Questions

1. Describe what happened to the temperature of the water as it was melting.

2. Hypothesize how the temperature of the water changed as it was freezing.

3. What happened to the temperature of the water after it melted?

4. What happened to the temperature of the water as it was heating?

5. What happened to the temperature of the water after it started boiling?

6. What was the temperature of your boiling water? The standard boiling temperature for water is 100 °C. Does your measurement agree with this? Explain why or why not.

7. Explain why temperature does not change during a phase change. Where does the heat energy go if not into increasing or decreasing temperature?

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