Question

What is the difference between specific heat capacity and heat rejected?

Answer 1

Specific Heat vs Heat Capacity

It is not surprising why many are confused between “specific heat” and “heat capacity.” It is because once you search for “specific heat” at online resources such as Wikipedia, you’ll automatically be redirected to the page for “heat capacity.” Well, “heat capacity” or “thermal capacity” is completely known as “specific heat capacity” which just adds to the confusion. By definition, the two are very similar. However, there’s just an additional variable included in specific heat that makes it differ a little as compared to heat capacity.

When you talk about “heat capacity” (having a symbol “C”), it is actually the heat needed for a substance’s temperature to change by one degree. This, therefore, shows that it is applicable to any type of matter. “Heat capacity” is the ratio of heat transfer “Q” to change in temperature “∆T.” In formulaic expression, it is C = Q / ∆T. In its SI unit notation, it uses units of energy / degree (energy per degree). It is expressed as the ratio of Joules (symbol “J” which stands for the value for energy) to Kelvin (symbol “K” which stands for the value of absolute temperature) C = J / K. In chemistry, however, they make use of molar heat capacity Cmol, which just adds the mol variable in the equation Cmol = J / mol . K.

On the other hand, “specific heat” sounds similar to heat capacity in terms of definition, but the former refers to the needed heat to adjust the temperature of a single unit of a substance’s mass by one degree. It makes use of energy / mass / degree units. C = J / kg . K. In here, the kg (kilogram) is the unit of mass included in the equation.

In terms of physical properties, “heat capacity” is the extensive variable because the quantity of a particular matter is directly proportional to its heat capacity. This means that the bigger the matter, the bigger is its resulting heat capacity (i.e. 2x matter gives you 2x heat capacity). By contrast, “specific heat” is an intensive variable, which means an attribute belonging to a specific substance and not to any matter in general. This makes it more convenient for scientists and other professionals to do experiments using the intensive variable.

Summary:

1.“Heat capacity” is an extensive variable while “specific heat” is an intensive variable.
2.“Specific heat” has a unit of mass in its equation as recommended by the International Standards of measurement.
3.“Specific heat” is more suitable for use in theoretical and experimental functions.
4.According to SI units, the formula for heat capacity is C = Q / ∆T while for specific heat it is C = J / kg . K.