part 2

Question 1

enthalpy of formation

Answer 1

heat energy transferred when 1 mole of a substance is formed in its standard state from its elements in their standard states

Question 2

standard conditions

Answer 2

298 K

1 atm

Question 3

aliphatic hydrocarbons

Answer 3

no benzene rings

Question 4

aromatic hydrocarbons

Answer 4

contains benzene rings

Question 5

where do Pi bonds of occour

Answer 5

carbon to carbon double bonds

Question 6

where do sigma bonds occur and why are they stronger

Answer 6

occur at single bonds, stronger as closer to nuclei

Question 7

What happens in catalytic cracking?

Answer 7

larger hydrocarbon molecules are heated with a catalyst and undergo thermal decomposition to form shorter hydrocarbons

Question 8

structural isomers definition

Answer 8

same molecular formula but different structural formula

Question 9

values different from experimental results

Answer 9

heat loss to surroundings
unable to maintain standard conditions
incomplete combustion

Question 10

values different from data books

Answer 10

bond enthalpies are averages

data book values are from elements all in their gaseous states