thermochemistry

Question 1

State Hess’s Law

Answer 1

Heat change for a reaction is independent of the path followed.

Question 2

Define heat of formation

Answer 2

Heat change or heat involved when one mole of a substance is formed from its elements in their standard states.

Question 3

Define heat of combustion

Answer 3

Heat change or heat released or produced or evolved when one mole of substance is burned in excess oxygen.

Question 4

Define heat of reaction

Answer 4

Heat change or heat involved in a certain chemical reaction.

Question 5

Exothermic Reaction

Answer 5

Heat is given off or released. ∆H is negative (temperature increases). Energy is released.

Question 6

Endothermic Reaction

Answer 6

Heat is absorbed or taken in. ∆H is positive (temperature decreases). Energy is taken in.

Question 7

What is the role of a catalyst?

Answer 7

A catalyst speeds up or slows down or alters or controls the rate of reaction but is not used up.