Chapter 9 Bond enthalpies

Question 1

Average bond enthalpy?

Answer 1

The energy required to break one mole of a specified type of bond in a gaseous molecule

Question 2

what does AVERAGE bond enthalpy describe in comparison to just bond enthalpy

Answer 2

Actual bond enthalpy can vary depending on the chemical environment of the bond:
The same bond can have several bond enthalpies in different compounds,
So a mean can be taken

Question 3

Is bond breaking endo or exothermic + pos or neg enthalpy

Answer 3

endothermic, positive bond enthalpy

Question 4

Is bond making exo or endothermic + pos or neg enthalpy

Answer 4

exothermic so enthalpy is neg

Question 5

What is the overall enthalpy change of a reaction in relation to

Answer 5

Difference in the energy required to break the binds in the reactants vs energy released from making the bonds in the products

Question 6

Equation for overall enthalpy change of a reaction

Answer 6

sum of bond enthalpies in reactants - sum of bond enthalpies in products

Question 7

Limitations of using average bond enthalpies in calculation

Answer 7

They are averages not the actual
All species are gaseous, not under standard conditions