Enthalpy Changes

Question 1

Enthalpy change

Answer 1

Heat energy transferred in a reaction at constant pressure

Question 2

Standard condition for pressure

Answer 2

100kPa

Question 3

⦵

Answer 3

Substances in standard state
Under standard conditions

Question 4

Are oxidation reactions exothermic or endothermic?

Answer 4

Exothermic

Question 5

2 examples of exothermic reactions

Answer 5

1) Combustion of fuel e.g.methane
2) Oxidation of carbohydrates

Question 6

2 examples of endothermic reactions

Answer 6

1) Thermal decomposition of calcium carbonate
2) Photosynthesis

Question 7

Standard enthalpy of combustion (ΔHc)

Answer 7

Enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions, with all the reactants and products in their standard state

Question 8

Standard molar enthalpy of formation

Answer 8

Enthalpy change when 1 mole of a substance is formed from its constituent elements under standard conditions, all reactants & products in their standard states

Question 9

Trigonal bipyramidal bond angle

Answer 9

90/120

Question 10

Symbol for enthalpy change

Answer 10

ΔH (delta H)

Question 11

Units of enthalpy change

Answer 11

kJ mol-1