Topic 4: Energetics

Question 1

What is the formula for the enthalpy change of combustion?

Answer 1

Enthalpy change of combustion: Delta H = A-B

Question 2

What is the formula for the enthalpy change of formation?

Answer 2

Enthalpy change of formation: Delta H = B-A

Question 3

What is the formula for the enthalpy change of a reaction?

Answer 3

Enthalpy change of a reaction: Delta H = (Sum of bonds broken) - (sum of bonds formed)

Question 4

What is the definition of the enthalpy change of formation?

Answer 4

when 1 mol of a compound is formed from its constituent elements in their standard states

Question 5

State Hess’s law

Answer 5

Enthalpy change is independent of the reaction route

Question 6

What is the definition of the enthalpy change of combustion?

Answer 6

When one mole of a compound is burnt completely in oxygen under standard conditions

Question 7

What is the formula of heat gain or loss?

Answer 7

Q= mass x specific heat capacity x change in temperature