5. Energetics

Question 1

Temperature

Answer 1

A measure of the average kinetic energy of particles

Question 2

Exothermic reaction

Answer 2

Heat energy is transferred from a system to the surroundings (surroundings get hotter)

Question 3

Endothermic reaction

Answer 3

A system takes in heat energy from the surroundings (the surroundings get cooler)

Question 4

Standard enthalpy change of combustion

Answer 4

The enthalpy change when one mole of a substance is completely burnt in oxygen under standard conditions

Question 5

Enthalpy change of solution

Answer 5

The amount of heat energy given out/taken in when 1 mole of solute dissolves in excess solvent

Question 6

Enthalpy change of formation

Answer 6

The enthalpy change when one mole of the substance is formed from its elements in their standard states under standard conditions

Question 7

Hess’s Law

Answer 7

The enthalpy change accompanying a chemical reaction is independent of the pathway between the initial and final states

Question 8

Average bond enthalpy

Answer 8

The energy required to break one mole of covalent bonds in a gaseous molecule under standard conditions (the average amount of energy to break a particular bond in a range of similar molecules)

Question 9

Entropy

Answer 9

A measure of how the available energy is distributed among the particles

Question 10

Spontaneous reaction

Answer 10

Reaction that occurs without any outside influence