Topic 5 - Bond Energies

Question 1

what happens to bonds during a chemical reaction?

Answer 1

old bonds are broken and new bonds are formed

Question 2

what type of process is bond breaking?

Answer 2

endothermic, as energy must be supplied to break the bonds

Question 3

what type of process is bond-forming?

Answer 3

exothermic, as energy is released when new bonds are formed

Question 4

what are the bond energies of endothermic reactions?

Answer 4

the energy used to break bonds is greater than the energy released by forming them

Question 5

what are the bond energies of exothermic reactions?

Answer 5

the energy released by forming bonds is greater than the energy used to break them

Question 6

what is bond energy?

Answer 6

each type of chemical bond has a particular bond energy

Question 7

how do you calculate enthalpy change with bond energies?

Answer 7

enthalpy change = total energy absorbed to break bonds - total energy released in making bonds

Question 8

what do positive/negative energy changes mean?

Answer 8

a positive energy change means an endothermic reaction
a negative energy change means an exothermic reaction