Energetics

Question 1

What is enthalpy of reaction

Answer 1

Enthalpy change when substances react under standard conditions

Question 2

What is standard enthalpy of formation

Answer 2

Enthalpy change when 1 mole of compound is formed from its elements with all reactants and products in standard states under standard conditions

Question 3

Standard enthalpy of combustion

Answer 3

Enthalpy change when 1 mole of a substance is burned completely in excess oxygen with all reactants and products in standard states under standard conditions

Question 4

What is hess law

Answer 4

Enthalpy change for a chemical reaction is independent of the route taken
Depends on initial and final states only

Question 5

What is the mean bond enthalpy

Answer 5

Measure of energy required to break one mole of a covalent bond measured in gaseous state
Bond breaking is endothermic
Bond making is exothermic
Shorter the covalent Bond the stronger the Bond
Triple > double > single