enthalpy

Question 1

ΔHr - standard enthalpy of reaction

Answer 1

enthalpy change that accompanies a reaction in the [molar quantities] shown in the [chemical reaction]
(standard conditions/state)

Question 2

ΔHf - standard enthalpy of formation

Answer 2

change in enthalpy when [1 mol. of product] is formed from its [elements]
(standard conditions/state)

Question 3

ΔHc - standard enthalpy of combustion

Answer 3

change in enthalpy when [1 mol. of a substance] is fully reacted with oxygen
(standard conditions/state)

Question 4

ΔHneut - standard enthalpy of neutralisation

Answer 4

change in enthalpy when [1 mol. of water (l)] is formed from an acid and base reacting
(standard conditions/state)

Question 5

is ΔH +/-

Answer 5

when energy is absorbed into the system, ΔH=+ (endothermic)
when energy is released from the system, ΔH= - (exothermic)

Question 6

standard conditions

Answer 6

25°C (298°K)
1 atm (100kPa)
standard states (both reactant and product)