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Su02 Distilled water a pure substance 2:
Changes of temperature during cooling and heating
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* Left: Even
if the environment is minus 10°C, it takes hours, to change for the
the freezing of water in a 5-ml
vial while
the volume increases.
* Photo 2 Observation:
Freezing started half an hour after transferring
20
ml distilled water into the
deep
freezer. It took 2 1/2 more hours of cooling for more freezing.
The thermometer showed 0°C all the time.
* After 3 hours heating
of the ice started. As long as ice was present the temperature remained
0°C.
* It took only 10 more minutes
for the temperature to rise to 100°C and boiling started.
* In spite of more heating
the temperature of the water remained 100°C.
Right: During the
distillation
experiment the temperature measured in the vapour above the Cola was
also
100°C.
Explanation:
During
melting
(boiling) the water consumes the heat to become liquid (gaseous).
So
its temperature remains 0°C (100)°C in spite of heating.
During
freezing
(condensation) water releases heat while it becomes solid (liquid).
So
its temperature remains 0°C (100)°C in spite of cooling.