Chemistry question below?

Question

Heat capacity is defined as the quantity of heat required to raise the temperature of a body by one degree Celsius. Does a negative heat capacity make sense?

Answer 1

Haha... I think you're using the same chemistry texts as me because I have the same exact question to answer for lab. This is what I think.

No, negative heat capacity does not makes sense because "as the heat capacity of an object increases, so does the amount of heat necessary to raise the temperature of the object." (the part in quotations is taken exactly from my text) This also means that the lower the heat capacity, the less amount of heat necessary to raise the temperature. Therefore, when the heat capacity is negative, it is saying that it is necessary to take away heat in order to raise the temperature of the object, which does not make sense.

Answer 2

The reason for your question is that someone gave you the incorrect definition for heat capacity! Look at what you wrote. You said that “heat capacity is the quantity of heat required to raise the temperature. . . “

There are two things about your definition that are incorrect. The first one is the work ‘heat’. Heat capacity is the quantity of energy in Joules) required. You cannot add heat to something. It is not as if you can put heat into a jar and then take some out and add it to something else. Believe it or not people used to think this about heat!

Actually, ‘heat’ is the energy that is transferred from one substance to another and it always goes from where there is a lot of energy as heat to where there is less.

The second problem in your definition is the word ‘raise’. Heat capacity is the energy required to change the temperature of a substance one degree Celsius, or one Kelvin.

So, you see why your question does not really make any sense? Heat capacity is neither positive or negative. It is just a number that tells you how much energy it takes to change the temperature of something.

The heat capacity of water is 1486J/kgK. This means that it takes 1486 Joules of energy to raise the temperature of one kilogram of water one Kelvin, if the energy is added; and it takes 1486 Joules of energy to lower the temperature of one kilogram of water one Kelvin, if the energy is taken away.

Answer 3

Does that question make sense