ENERGETICS DEFINITIONS

Question 1

Enthalpy change

Answer 1

Heat energy change in reaction at constant pressure

Question 2

Standard conditions

Answer 2

100 kPa, 298 K, 1 moldm-3 concentration of ions

Question 3

Standard enthalpy change of reaction

Answer 3

Enthalpy change when reaction occurs in the molar quantities shown in the chemical reaction under standard conditions

Question 4

Standard enthalpy change if formation

Answer 4

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

Question 5

Standard enthalpy change of combustion

Answer 5

Enthalpy change when 1 mol of a substance is completely burned in oxygen under standard conditions

Question 6

Standard enthalpy change of neutralisation

Answer 6

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

Question 7

Specific heat capacity

Answer 7

The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree

Question 8

Hess’s law

Answer 8

Total enthalpy change is independent of the reaction pathway taken

Question 9

Bond enthalpy

Answer 9

Amount of energy required to break 1 mol of stated bond in the gas phase

Question 10

Mean bond enthalpy

Answer 10

Average amount of energy needed to break a specific type of bond, measured over a variety of different molecules