# What does a high specific heat tell about a substance?

Jul 15, 2017

Specific heat capacity is a measure of how much heat energy a material can hold per kilogram per kelvin, its units are usually given as "kJ kg"^-1" K"^(-1), or ("kJ")/("kg K").

If an object's specific heat capacity was $1 {\text{kJ kg"^-1" K}}^{-} 1$. The it will hold $1 k J$ of thermal energy for every kilogram with a temperature increase of $1 K$, or it will hold $1 k J$ of thermal energy for every 1°K change in temperature at a constant mass.

A high specific heat capacity means it can hold a large amount of thermal energy in for a low mass or temperature change. It is also good at keeping in thermal energy, for example:

Object:
Mass = 3kg
$\Delta T$ = 10K
S.H.C. = 3.5 ${\text{kJ kg}}^{-} 1$${\text{K}}^{-} 1$

Liquid:
Mass = 3kg
$\Delta T$ = 2K
S.H.C = ?

${m}_{o} {C}_{o} \Delta {T}_{o} = {m}_{l} {C}_{l} \Delta {T}_{l}$
$\Delta {T}_{l} = \frac{{m}_{o} {C}_{o} \Delta {T}_{o}}{{m}_{l} {C}_{l}} = \frac{3 \cdot 10 \cdot 3.5}{3 \cdot 2} = 17.5 {\text{kJ kg}}^{-} 1$${\text{K}}^{-} 1$.

As you can see, because of the liquid's high S.H.C. it gained the same amount of heat energy as the object lost, with a smaller temperature change.