# Specific heat units

Hopefully this is a really simple question to answer. A problem I have uses the following information:

The specific heat of air = 1.05 kJ/hg-C.

Does anyone know what the hg-C stands for? I know specific heat is usually expressed in terms of J/C, so this is confusing me.

## Answers and Replies

The units of specific heat are energy per unit of mass per unit of temperature. Thus it should read kJ/(kg C). I think you misread the unit and ended up with hg instead of kg.

Nope, I double checked and the units are definitely kJ/(hg-C). Any ideas as to what the hg may be? Is it some reference to mercury?

It doesn't refer to mercury. Let's say it's a typing mistake. I stand by my previous post

The specific heat of air is of the order of 1 kJ/kg.K (or kJ/kg.C). The exact value depends on temperature. So it is a typo, no doubt.
The units J/C (asuming C stands for Celsius degree) are for heat capacity and not for specific heat.