Energetics

Question 1

How do you calculate overall enthalpy change (ΔH)?

Answer 1

ΔH= energy to break bonds (+ve) + energy to make bonds (-ve)

Question 2

What is the standard condition?

Answer 2

100kPa and 298k

Question 3

Define enthalpy of formation

Answer 3

The enthalpy change when one mole of a substance is produced from its elements under standard conditions.

Question 4

Define enthalpy of combustion

Answer 4

The enthalpy change when one mole of a substance is burned completely in oxygen under standard conditions

Question 5

Define specific heat capacity

Answer 5

the energy required to raise 1kg of substance by 1 degree

Question 6

What is the equation for specific heat capacity and how can we use this to calculate enthalpy change?

Answer 6

q=mcΔT

ΔH= q/moles

Question 7

Define hess’s law

Answer 7

The overall enthalpy change for a reaction is the same regardless of the route taken.

Question 8

Bond enthalpy data is an averaged value representing what?

Answer 8

The energy required to break one mole of the stated bond in a gaseous state, under standard conditions