Energetics

Question 1

Enthalpy change

Answer 1

Heat energy change at constant pressure

Question 2

Hess’s law

Answer 2

The enthalpy change in a reaction is independent of the route

Question 3

Bond enthalpy

Answer 3

Enthalpy change required to break a covalent bond

Question 4

Exothermic

Answer 4

releases energy, products have less energy than the reactants

EC is -

Question 5

Endothermic

Answer 5

Absorbs energy, products have more energy than the reactants

EC is +

Question 6

Standard enthalpy change of formation

Answer 6

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

Question 7

Standard enthalpy change of combustion

Answer 7

the enthalpy change that occurs when 1 mole of a substance is combusted completely in oxygen under standard conditions, with all the reactants and products being in their standard states.

Question 8

standard conditions

Answer 8

A pressure of 100 kPa (1 atmosphere), a stated temperature, usually 298 K (25 °C), and a concentration of 1 mol dm-3 (for reactions with aqueous solutions).