Question

What does a high specific heat tell about a substance?

Answer 1

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"kJ kg"^-1" K"^-1`. The it will hold `1kJ` of thermal energy for every kilogram with a temperature increase of `1K`, or it will hold `1kJ` 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
`DeltaT` = 10K
S.H.C. = 3.5 `"kJ kg"^-1` `"K"^-1`

Liquid:
Mass = 3kg
`DeltaT` = 2K
S.H.C = ?

`m_oC_oDeltaT_o=m_lC_lDeltaT_l`
`DeltaT_l=(m_oC_oDeltaT_o)/(m_lC_l)=(3*10*3.5)/(3*2)=17.5"kJ kg"^-1` `"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.