Topic 8 Lesson 1 Core Qs

Question 1

Entahlpy change

Answer 1

The amount of heat energy given out or taken in during a reaction in the system at a constant pressure

Question 2

What sign does an exothermic reaction have

Answer 2

Negative

Question 3

What sign does an endothermic reaction have

Answer 3

Positive

Question 4

What is meant by an exothermic reaction

Answer 4

A reaction which transfers energy to surroundings (reactants have more energy than producrs)

Question 5

What is meant by an endothermic reaction

Answer 5

A reaction which takes in energy from the surroundings (reactants have less energy than products)

Question 6

Example of exothermic reaction

Answer 6

Combustion of fuels/neutralisatuon

Question 7

Example of endothermic reaction

Answer 7

Thermal decomposition

Question 8

Standard conditions

Answer 8

Temp of 298K, pressure 100kPa, conc 1mol dm-3

Question 9

Standard enthalpy change of formation

Answer 9

Enthalpy change occurs when 1 mole of a compound is formed from its elements under standard conditions with all reactants and products in standard states

Question 10

Standard enthalpy change of combustion

Answer 10

1 mole of a substance reacts completely with oxygen under standard conditions

Question 11

What is the enthalpy change of formation of an element equal to

Answer 11

0kJ mol-1

Question 12

2 products formed in combustion of fuels

Answer 12

CO2 and H2O

Question 13

What gas is formed in incomplete combustion

Answer 13

Carbon monoxide

Question 14

Enthalpy change of reaction

Answer 14

The enthalpy change which occurs when equation quantities of materials react under standard conditions and with all substances in their standard state

Question 15

Define enthalpy change of neutralisation

Answer 15

Enthalpy change when an acid and alkali react together to form 1 mole of water under standard conditions

Question 16

Formulas

Answer 16

Mass=Mr moles
q=mC (delta)T
pV=nRT (R=8.31)
Conc=moles/volume
1dm3=1000cm3
Mass of solute=molesxMr