How To Calculate Energy Released & Absorbed

Every chemical reaction either absorbs or releases energy. Energy is described in kilojoules per mole, which is a unit of measurement reflecting the amount of energy stored within a material. To determine how your chemical reaction is using energy, you will need to take specific measurements of the reaction itself, then calculate those values using a standard equation. These steps are recommended for those with a basic understanding of working with chemical reactions. Make sure that you are wearing proper safety equipment and that you are familiar with the chemicals being used.

Step 1

Research the specific heat capacity value for your first reactant. See the Resource links for lists of the heat capacities of many common substances.

Step 2

Fill two separate containers with the reactants. Weigh each container to determine the mass of the reactant. Record these measurements in grams.

Step 3

Measure the temperature of the first reactant with a thermometer. Record this measurement.

Step 4

Add the second reactant to the first container. Measure the temperature of the combined reactants. Record this value.

Step 5

Insert the measurements taken from the previous steps into the following equation:

Energy = (mass of first reactant + mass of second reactant) x Specific Heat Capacity x (temperature of first reactant – temperature of combined reactants)

This equation will calculate the number of kilojoules per mole released by the first reactant. To determine the energy absorbed, assign a negative value to the equation's solution.

Things Needed

  • Two or more chemical reactants
  • Two or more chemistry containers (flasks, beakers, etc.)
  • Standard lab thermometer
  • Notepad and pen
  • Calculator (recommended)
  • Safety goggles and gloves

Cite This Article

MLA

Cartwright, Marie. "How To Calculate Energy Released & Absorbed" sciencing.com, https://www.sciencing.com/calculate-energy-released-absorbed-7485946/. 13 March 2018.

APA

Cartwright, Marie. (2018, March 13). How To Calculate Energy Released & Absorbed. sciencing.com. Retrieved from https://www.sciencing.com/calculate-energy-released-absorbed-7485946/

Chicago

Cartwright, Marie. How To Calculate Energy Released & Absorbed last modified August 30, 2022. https://www.sciencing.com/calculate-energy-released-absorbed-7485946/

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