Specific Heat Capacity and Thermal Energy Transfer Notes

Definition of Specific Heat Capacity

• Specific heat capacity is defined as the amount of heat required to raise the temperature of $1\,g$ of a substance by $1^{\circ}C$.

• There is an inverse relationship between the magnitude of a substance's specific heat capacity and the speed at which its temperature changes:

  • The higher the specific heat capacity, the longer it takes to heat that substance.

  • Conversely, a lower specific heat capacity means the substance will heat up more quickly.

• It is a significant characteristic that water possesses a very high specific heat capacity compared to many other common substances.

Mathematical Formula for Temperature Changes

• To calculate the energy involved in temperature changes, use the following formula:

  • $Q = mc\Delta T$

• Note on Usage: This specific formula is intended for use only during temperature changes and not during phase changes.

• Variable Definitions:

  • $Q$ represents the amount of heat or energy, measured in Joules ($J$).

  • $m$ represents the mass of the substance, measured in grams ($g$). If the mass is provided in other units (such as kilograms), it must be converted to grams first.

  • $c$ represents the specific heat capacity, measured in Joules per gram degree Celsius ($J/g^{\circ}C$). These values can typically be found in a provided data booklet.

  • $\Delta T$ represents the change in temperature, measured in degrees Celsius ($^{\circ}C$).

• Energy Sign Conventions:

  • When $Q = +ve$ (a positive value), heat/energy is being absorbed by the substance.

  • When $Q = -ve$ (a negative value), heat/energy is being released by the substance.