How To Calculate Heat Absorbed By The Solution

Although laymen often use the terms "heat" and "temperature" interchangeably, these terms describe different measurements. Heat is a measure of molecular energy; the total amount of heat depends upon the number of molecules, dictated by the mass of the object. Temperature, on the other hand, measures the average energy of each molecule. To determine the amount of heat energy absorbed by a solution, you must do more than find its temperature. You must also know its specific heat, or the amount of energy required to raise one gram of the substance 1 degree Celsius.

Step 1

Measure the mass of the empty container and the container filled with a solution, such as salt water.

Step 2

Subtract the mass of the empty container from the mass of the full container to determine the mass of the solution.

Step 3

Measure and record the solution's temperature before you heat it.

Step 4

Heat the solution, then measure and record its new temperature.

Step 5

Subtract its initial temperature from its final temperature. Record the difference as the temperature change.

Step 6

Find the solution's specific heat on a chart or use the specific heat of water, which is 4.186 joules per gram Celsius.

Step 7

Substitute the solution's mass (m), temperature change (delta T) and specific heat (c) into the equation Q = c x m x delta T, where Q is the heat absorbed by the solution. For example, if a solution of salt water has a mass of 100 g, a temperature change of 45 degrees and a specific heat of approximately 4.186 joules per gram Celsius, you would set up the following equation — Q = 4.186(100)(45).

Step 8

Simplify the equation. The answer is the absorbed heat measured in joules. The salt water absorbed 18,837 joules of heat.