Question

Name and state the principle used to measure the specific heat capacity of a substance.

Hint:

The method of mixtures is a practical application of the conservation of energy, where energy lost equals energy gained. It is often used in calorimetry to determine specific heat capacities.

Answer 1

The principle used to measure the specific heat capacity of a substance is the Principle of Heat Exchange, applied through the Method of Mixtures. Statement of the Principle: The principle of heat exchange states that when two or more objects at different temperatures are brought into thermal contact and isolated from their surroundings, the heat lost by the hotter object(s) is equal to the heat gained by the colder object(s) until thermal equilibrium is reached. This can be expressed mathematically as: \[ \text{Heat lost by hot body} = \text{Heat gained by cold body} \] Mathematically, the heat transferred ($Q$) can be calculated using the formula $Q = mc\Delta T$, where $m$ is mass, $c$ is specific heat capacity, and $\Delta T$ is the change in temperature. In the method of mixtures, a substance of known mass and temperature is mixed with another substance (often water in a calorimeter) of known mass and temperature. By measuring the final equilibrium temperature, the unknown specific heat capacity can be calculated.