energy changes in equations 4.3 chemistry

law of conservation of energy

energy cannot be created or destroyed, but can be changed

to break bonds is to

release stored chemical energy

exothermic reactions

hot

energy is released by system to surroundings

endothermic reactions

cold

heat absorbed by system from surroundings

exothermic equations

negative DELTA H

kJ leaves the system

CH₄+O₂→Co₂+H₂O+300kJ

endothermic equations

gain energy, kJ on reactant side

CO₂+H₂O+kJ→O₂+C₆H₁₂O₆

_{DELTA H positive}

endothermic energy diagram

exothermic energy diagram

what is shown in Exothermic energy diagram?

reactants have more stored chemical energy than products

energy is released

feals hot

what is shown in endothermic energy diagrams>

products have more stored chemical energy than reactants

energy is absorbed during reaction

cold