Calculation of Average Rate of Heat Transfer

1. Heat is transferred when kinetic energy is transferred from molecules with higher kinetic energy to molecules with lower kinetic energy. The average rate of heat transfer is the change in temperature of a substance or a reaction over a given period of time.

2. To calculate the average rate of heat transfer, determine the higher temperature of the substance or reaction and the lower temperature of the substance or reaction during the course of the experiment. Determine the time needed for the experiment to take place.

3. When calculating the average rate of heat transfer, the temperature is usually recorded in degrees Celsius (^oC).

4. When calculating the average rate of heat transfer, time is usually recorded in minutes (min) or seconds (sec).

5. The average rate of heat transfer is generally reported as degrees Celsius per minute (^oC/min) or degrees Celsius per second (^oC/sec).

6. The average rate of heat transfer is equal to the difference in the higher and lower temperatures divided by the time used for the experiment. It can be written as the following formula:

For example, a beaker of water has an initial temperature of 6 ^oC. After 45 minutes, the final temperature is 18 ^oC. The higher temperature is 18 ^oC and the lower temperature is 6 ^oC. The time for the experiment is 45 minutes. The average rate of heat transfer is calculated as: