# Effect of specific heat of a substance on the rate of heat flow

1. Apr 2, 2009

### emporia

I have been wondering, does specific heat capacity affect the rate of heat flow from one substance to another?

For example if the substances at heated up to the same temperature then left outside until thermal equilibrium is reached. I would think the one with the larger specific heat capacity (substance x) cools at a faster rate as the energy difference between it and the atmosphere is greater than the one with a smal specific heat (substance y).

The larger the energy difference the greater the rate of heat flow. As this energy difference becomes smaller due to the substance the rate of flow would lessen.

The rate of heat flow behaves similarly to an exponential funtion, therefore am i correct in assuming that the affect of specific heat on heat flow is offset by the decrease of the energy difference effectively cancelling out the effect of specific heat?

Last edited: Apr 2, 2009
2. Apr 2, 2009

### chemisttree

Energy difference isn't what is important. Temperature difference is. Surface area is. All things being equal, the material with the greatest heat capacity will resist a change in temperature more so than one with a small heat capacity.

That is kind of the definition of heat capacity, y'know.

3. Apr 2, 2009

### Staff: Mentor

No. Heat transfer coefficient is the only thing that counts.

4. Apr 2, 2009

### emporia

Thanks for that.
I'm just puzzled now that my chemistry teacher agreed with me on the previous explanation but was doubtful when i suggested that heat capacity doen't affect heat flow.

5. Apr 2, 2009

### Staff: Mentor

Well... there is a heat flow and there is a heat flow

Say you have two bodies of different temperatures. Net heat flow is that from the hotter body to the colder body. Amount of the the heat that flows in the time unit is just a power - and this power doesn't depend on the heat capacity, in any given moment it depends on the temperature difference, geometry of the system and heat capacity coefficient. Period.

Now, if you are interested not in in a situation at any given time point, but in the changes of the temperature in a long period of time, knowing just power transmitted in any moment is not enough. You have to account for heat capacity of the system, as it will change the speed at which temperature of the different parts of the system will change - changing heat flow (power).