chemical energy

Question 1

what is enthalpy?

Answer 1

a measure of the chemical energy in a substance

change in energy in a chemical reaction

Question 2

what is enthalpy of combustion?

Answer 2

when one mole of substance is burned completely in oxygen

Question 3

what are the experimental concerns of using a calorimeter ?

Answer 3

the values obtained for the enthalpy of combustion are lower than theoretical value
not all fuels combust due to heat loss

Question 4

what is hess’s law?

Answer 4

the enthalpy change of a chemical reaction is independent of the route taken
enthalpy change for the direct route is equal to the sum of the enthalpy changes for all routes

Question 5

what is bond enthalpies used for?

Answer 5

calculate the enthalpy change for chemical reactions
breaking bonds requires energy
making bonds releases energy

Question 6

what is the combustion value always?

Answer 6

negative value