8 - HEAT OF FUSION OF ICE AND HEAT OF VAPORIZATION OF WATER

Question 1

We use the term _______ to describe a specific state of matter such as a solid, liquid or gas.

Answer 1

phase

Question 2

A transition from one phase to another is called a _______.

Answer 2

phase change

Question 3

For any given pressure, a phase change takes place at a definite temperature usually accompanied by (2)

Answer 3

• absorption or emission of heat
• a change of volume and density

Question 4

At normal atmospheric pressure, heat transfer Q in a phase change is _______. The plus sign is when heat is absorbed or entering, the minus sign when heat is leaving.

Answer 4

Q= +/-mL

Question 5

When solid changes to liquid or liquid to solid, L is called ______ denoted by Ls.

Answer 5

heat of fusion

Question 6

For ice, Lf is ______ at 0°C.

Answer 6

3.34x10^5 J/Kg

Question 7

T or F
For any given material at any given pressure, the freezing temperature is the same as the melting temperature.

Answer 7

T

Question 8

At this unique temperature, the liquid and solid phase can coexist in a condition called

Answer 8

phase equilibrium.

Question 9

When liquid changes to gas or gas to liquid, L is called __________ denoted by Lv

Answer 9

heat of vaporization

Question 10

For water, Lv has a value equal to

Answer 10

2256x10^3 J/Kg

Question 11

Connect a rubber tubing from the steam generator to the water trap and another one from the water trap to the calorimeter. (Note: the rubber tubing from the steam generator to the water trap must be longer than the rubber tubing from the water trap to the calorimeter. The water trap must have two holes, one for the incoming steam and another for the steam to be introduced to the inner calorimeter.)

Question 12

Why is it that you need a water trap in performing this experiment? Why can’t you introduce the steam directly to the calorimeter cup?

Answer 12

To make sure only steam enters the calorimeter and no other substances such as droplets of water (condensed water) which could interfere with the mass

Question 13

What is the importance of wiping the ice dry before introducing it to the water in the calorimeter? How would it affect the outcome of the experiment?

Answer 13

To ensure that no extra water, which has already melted, enters the system. It could lower heat of fusion.