Enthalpy

Question 1

Mean bond enthalpy definition

Answer 1

Required energy to break 1 mol of a gaseous covalent bond averaged across many compounds containing the bond.

Question 2

Problems with calorimetry ?

Answer 2

• Some heat will be absorbed by the container rather than heating up the water.
• Some heat will always be lost to the surroundings.

Question 3

What is specific heat capacity ?

Answer 3

Energy required to the temperature of 1g of a substance by 1 degree celsius.

Question 4

Standard enthalpy change of reaction definition.

Answer 4

Enthalpy change when reaction occurs in molar quantities shown in chemical equation. Standard conditions and states.

Question 5

Enthalpy changes of formation definition

Answer 5

Enthalpy change when 1 mol of a compound is formed from its elements under standard condition. Reactants and products in standard states.

Question 6

What is Hess’s Law ?

Answer 6

States enthalpy change for chemical reaction is the same whatever route is taken from reactants to products.

Question 7

Enthalpy of reaction equation ?

Answer 7

Products - Reactants

Question 8

Enthalpy of formation equation ?

Answer 8

Reactants - products