Calculating And Explaining Energy Change

Question 1

The relative amounts of energy released when substances burn can be measured by:

Answer 1

Simple calorimetry. e.g. by heating water in a glass or metal container. This method can be used to compare the amounts of energy released by fuels and foods

Question 2

What is energy normally measured in?

Answer 2

joules

Question 3

The amount of energy released or absorbed by a chemical reaction in solution can be calculated from…

Answer 3

The measures temperature change of the solution when the reagents are mixed in an insulated container this method can be used for reactions of solids with water or for neutralisation reactions

Question 4

During a chemical reaction:

Answer 4

energy must be supplied to break bonds

energy is released when bonds are formed

Question 5

What is an exothermic reaction?

Answer 5

The energy released from forming new bonds is greater than the energy needed to break existing bonds

Question 6

What is an endothermic reaction?

Answer 6

The energy needed to break existing bonds is greater than the energy released from forming new bonds

Question 7

What do catalysts provide?

Answer 7

a different pathway for a chemical reaction that has a lower activation energy

Question 8

What can hydrogen be used for?

Answer 8

It can be used as a fuel in combustion engines
Hydrogen + Oxygen —–> water
It can also be used in fuel cells that produce electricity to power vehicles