Question

What is chemical energy measured in?

Answer 1

The “Official” standard is the Joule in the SI system (International System of Units) in much of the world.

Explanation:

Other measures are still often used in various places, due to history or culture. The BTU (British Thermal Unit) is still used in many home and industrial heating and energy applications.

1 Joule (J) is the MKS unit of energy, equal to the force of one Newton acting through one meter (N-m). 1 Watt is the power of a Joule of energy per second (J/s).

Some other systems and conversions can be found here:
https://www.eia.gov/energyexplained/index.cfm?page=about_energy_units
and here:
https://www.physics.uci.edu/~silverma/units.html