Scientific Tutor

HOW IS ENERGY REPRESENTED IN A CHEMICAL EQUATION?

Energy can be connected in different ways to a chemical equation. The first and easiest to recognize is when energy is presented in a chemical equation like the examples below.

200kJ + N_2(g) + 3 H_2(g) —-> 2 NH_3(g)

Above the energy shown on the LEFT SIDE of the arrow (yield sign) by the number and units 200kJ.  This is an example of a chemical reaction that absorbs energy. In chemistry they call this an ENDOTHERMIC (or ENDERGONIC) reaction.

2 H₂O_(g) —-> 2 H_2(g) + O_2(g) + 147cal

Above the energy shown on the RIGHT SIDE of the arrow (yield sign) by the number and units 147cal. This is an example of a chemical reaction that releases energy. In chemistry they call this an EXOTHERMIC (or EXERGONIC) reaction.