Energy Calculations

Energy Calculations

The energy of absorption or release depends on each equation

Exothermic reactions have the energy on the right hand side and a negative H

Endothermic reactions have the energy on the left hand side and a positive H

H is the energy of charge of a reaction and is expressed in JK per mole of the chemicals

CH4+2O2 à CO2+2H2O+812KJ

-812/1mol CH4

-812/2mol O2 (-406)

-812/1mol CO2

-812/2mol 2H2O (-406)

0.45 mol H2O * -812/2mol 2H2O = -190KJ

2500 energy release

 -2500*1mol CH4 / -812 = 3.1mol of CH4

How many gram of O2 would needed to produce 2500KJ of energy?

-2500* 2mol O2/-812 = 6.2 moles of O2

6.2 moles of O2 * 32g/1 mol = 200 of O2