5.2.1 - enthalpy changes

Question 1

what is the enthalpy change of a reaction

Answer 1

the heat energy it releases or absorbs per mole

Question 2

what is the symbol for enthalpy change

Answer 2

ΔH

Question 3

what does a positive sign before an enthalpy change show and what type of reaction would it be

Answer 3

shows heat energy is absorbed

it is endothermic

Question 4

what does a negative sign before an enthalpy change show and what type of reaction would it be

Answer 4

heat energy is released

exothermic reaction

Question 5

what are the units for enthalpy change

Answer 5

kJ/mol

Question 6

what does how much heat energy a reaction absorbs or releases depend on

Answer 6

• breaking bonds, which absorbs energy
• making bonds, which releases energy

Question 7

what does it mean in terms of energy if a reaction is endothermic

Answer 7

the products end up with more energy than the reactants

Question 8

what does it mean in terms of energy if a reaction is exothermic

Answer 8

the products end up with less energy than the reactants