Question

In case of a burn you would use?

• Ice at 10^@C
• Water at -2^@C

Solution:

The first question many students asked us was:

How can water exist at -2^@C? How can ice exist at 10^@C?

Melting and boiling point of water is not fixed and there many factors which influence it like the pressure applied, presence of impurities. So it possible to raise, lower the melting point of water.

Now coming back to the question. We need to find the material which is going to absorb more energy.

Specific heat of water if 4.2J/g while the latent heat of ice is 330J/g.

While taking water from -2^@C to 10^@C will absorb 12*4.2=50.4J

But converting ice to water at 10^@C will require 330J.

So Ice at 10C appears much colder than water at -2^@C