Chapter 9 Enthalpy

Question 1

What is an exothermic reaction?

Answer 1

Heat transfers to the surroundings- negative enthalpy change

Question 2

What is an endothermic reaction?

Answer 2

Heat transfers from the surroundings- positive enthalpy change

Question 3

What is the equation for the standard enthalpy change of reactions?

Answer 3

△rH^0

Question 4

What is the standard enthalpy change of reactions?

Answer 4

The enthalpy change that occurs when a chemical reaction occurs under standard conditions in the stoichiometric ratios in the balanced equation.
Eg CaCO3 —> CaO + CO2
2CaCO3 —> CaO + CO2
—> 2 x △rH^0

Question 5

What is the standard enthalpy change of combustion?

Answer 5

The enthalpy change that occurs when one mole of a substance completely combusts in oxygen under standard conditions.

Question 6

What is the equation for the standard enthalpy change of combustion?

Answer 6

△cH^0

Question 7

What is the standard enthalpy change of formation?

Answer 7

The enthalpy change that occurs when one mole of a compound is formed from its elements in their standard states under standard conditions

Question 8

What is the equation for the standard enthalpy change of formation?

Answer 8

△fH^0

Question 9

What is the standard enthalpy change of neutralisation?

Answer 9

The enthalpy change reaction that occurs when one mole of water is formed from the reaction of an acid and base under standard conditions

Question 10

What is the equation for the standard enthalpy change of neutralisation?

Answer 10

△nH^0

Question 11

What is the enthalpy change equation?

Answer 11

q= mc △T
q~ Energy J
m~ mass of substance
c~ Specific heat capacity
△T~ Change in temperature- unit does not matter