Hot and Cold Lab Recap

Boiling water graph

Time in seconds

Temperature in C

At 100 degrees the water begins

to boil.

What’s happening?The water rises steadily until it reaches 100

degrees.It levels out at 100Why does the water temperature not rise

above 100 degrees even if you keep heating it? (where is that energy going?)

BoilingBoiling is when you change a liquid to a gas

by giving it enough heat (ENERGY) so it can break free of the attraction it has to the other water droplets.

When water reaches 100 degrees, some of the water molecules get enough energy to turn into a gas. If you kept heating it, more and more of the liquid would be boiling and becoming a gas.

Freezing water graph

Time in seconds

Temperature in C

At zero degrees the

water begins to freeze

When the water is totally

frozen the temperature

begins to drop again

What’s Happening?When you cool the water down you are taking

energy from it! (Remember, the salt melts the ice on the outside, so it takes energy to turn the ice into a liquid).

Why does the temperature flat line and then drop?

FreezingThe temperature drops once the ice is frozen

solid. Zero degrees is when the water begins to

turn to ice. When it starts dropping again the ice is frozen solid and the energy that is being stolen can go towards lowering the temperature of the solid.