Temperature Change

Empirical Law: Temperature Change

The change $\Delta T$ in the temperature $T$ of a physical system depends on the heat $Q$ which flows into or out of it:

• If heat flows into the system $(Q>0)$, then its temperature increases $(\Delta T>0)$.
• If heat flows out of the system $(Q<0)$, then its temperature decreases $(\Delta T<0)$.

When the temperature change is relatively small, the heat required to achieve it is approximately proportional to it:

• The heat $Q$ can be expressed via the mass $m$ and the specific heat capacity $c$ of the substance.

$$Q=cm\Delta T$$

• The heat $Q$ can be expressed via the moles $n$ and the molar heat capacity $c_m$ of the substance.

$$Q=c_{m}n\Delta T$$