Question

Table 1: Temperature of Frozen Water Over Time
Time (min.)	Temperature (°C)	Observation
0	-12	Water is frozen
5	0	Water is frozen
10	1	Ice is attached to thermometer but unstuck from test tube
15	14	There is a pool of water in the bottom of the test tube
20	2	The pool of water is flightly bigger, ice chunk is getting smaller
25	4	The ice chunk is over halfway melted
30	5	The Ice chunk is over halfway melted

Table 2: Temperature of Boiling Water Over Time
Time (min.)	Boiling Temperature (°C)
1	97
5	97

1. Look at your data in Table 1. What was the last measured temperature before the all ice melted (so it was still mixture of ice and water)?
2. Look at your data in Table 1. Describe what happened to the temperature of the water as during melting process
3. What happened to the temperature of the water after it melted?
4. Based on your observation of temperature during melting process hypothesize how the temperature of the water changed during freezing process.

5. What happened to the temperature of the water, which was placed on the oven top, during the heating process?

6. Look at your data in Table 2. What happened to the temperature of the water after it started boiling?

7. 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.

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

Answer 1

Sol: from table 1

The last temperature before ice melted is 5°C.

During melting process the temperature of water first increases then decreases , when ice melted the temperature of the water start to increase until it becomes equal to surrounding temperature.

For freezing process the temperature of the water must decrease to 0°C , water will become ice at this temperature.

During heating process the temperature of water start to increase upto its boiling point.

After water start to boil the temperature remain constant.

Temperature of your boiling water is 97°C, this is slightly lower than that of standard value which is taken at standard pressure which is 1 atm, this happen due to the less pressure in surrounding which is lower than 1 atm.

Water boil when its pressure becomes equal to its surrounding.

Temperature doesn't change during a phase change it remain constant because the heat will get used in breaking the bond or forming the bond.

Heat transferred just change the phase.