Module 3: Enthalpy (Chapter 9)

Question 1

Define standard conditions

Answer 1

Pressure = 100 kPa 
Temperature = 298K
Concentration = 1 mol dm3

Question 2

Define standard states

Answer 2

The physical state of a substance under standard conditions

Question 3

Define enthalpy change of reaction

Answer 3

Enthalpy change that accompanies a reaction in molar quantities shown in a chemical equation uder standard conditions

Question 4

Define enthalpy of formation

Answer 4

Enthalpy change when 1 mole of a compound is formed from its elements in their standard states, under standard conditions

Question 5

Define enthalpy of combustion

Answer 5

Enthalpy change when 1 mole of a reactant is burnt completely in oxygen, under standard conditions

Question 6

Define enthalpy of neutralisation

Answer 6

Enthalpy change when 1 mole of water is formed from neutralisation under standard conditions

Question 7

Define enthalpy

Answer 7

The measure of the heat energy in a chemical system. Units are kJ mol-1

Question 8

Enthalpy change of reaction exo or endo

Answer 8

Both exo and endo

Question 9

Enthalpy of formation exo or endo

Answer 9

Both exo and endo

Question 10

Entalpy of combustion exo or endo

Answer 10

Exo

Question 11

Enthalpy of neutralisation exonor endo

Answer 11

Both exo and endo

Question 12

Define activation energy

Answer 12

Minimum energy required for a reaction to take place

Question 13

What does a low Ea mean?

Answer 13

Rapid recation as energy is readily available from surroundings

Question 14

What does a high Ea mean?

Answer 14

Energy barrier very high menaing reaction occurs slowly or not at all

Question 15

Equation for calculating energy

Answer 15

Q=mcT

Question 16

How to calculate ethalpy with know energy value?

Answer 16

Energy/moles

Question 17

% error calculation

Answer 17

(Accepted value-expected value)/accepted value