Energy Changes

Question 1

Activation Energy

Answer 1

The minimum amount of energy for particles to collide with in order for a successful reaction to occur.

Question 2

Alkaline Batteries

Answer 2

Alkaline batteries are non-rechargeable. In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up.

Question 3

Battery

Answer 3

Batteries consist of two or more cells connected together in series to provide a greater voltage.

Question 4

Chemical Cells

Answer 4

Cells contain chemicals which react to produce electricity.

Question 5

Endothermic Reaction

Answer 5

A reaction that takes energy from the surroundings so the temperature of the surroundings decreases. The energy needed to break existing bonds is greater than the energy releases from forming new bonds.

Question 6

Exothermic Reaction

Answer 6

A reaction that transfers energy to the surroundings so the temperature of the surroundings increases. The energy released from forming new bonds is greater than the energy needed to break existing bonds.

Question 7

Fuel Cells

Answer 7

Fuel cells are supplied by an external source of fuel (e.g. hydrogen) and oxygen or air. The fuel is oxidised electrochemically within the fuel cell to produce a potential difference.

Question 8

Overall Energy Change of the Reaction

Answer 8

The difference between the sum of the energy needed to break bonds in the reactants and the sum of the energy released when bonds in the product are formed.

Question 9

Reaction Profile

Answer 9

Reaction profiles can be used to show the relative energies of the reactants and products, the activation energy, and the overall energy change of a reaction.

Question 10

Rechargeable Cells

Answer 10

Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.