Atoms, Elements, compounds, Chemical reactions A290 – 97

Question 1

What is a fuel?

Answer 1

A substance that stores energy in a chemical store.

Question 2

What happens in a combustion reaction?

Answer 2

The fuel reacts with oxygen and energy is transferred to the surroundings as heat and light.

Question 3

What happens in a methane combustion

Answer 3

• Methane and oxygen combust to form carbon dioxide and water
  CH4 + 2 O2—>CO2 + H2O + H2O

Question 4

Why is ethanol a renenwable fuel?

Answer 4

You need sugar cane crops to make ethanol, so the crops remove CO2 from the air as they grow.

Question 5

What is a decomposition reaction?

Answer 5

A simple compount being broken down into simpler compounds or elements.

Question 6

Describe the decomposition reaction in 2 Hydrogen peroxide molecules

Answer 6

H2O2 + H2O2 –> H2O + H2O + O2

Question 7

Describe the thermal decomposition in a copper carbonate molecule.

Answer 7

CuCO3 –> CuO + CO2

Question 8

State what conservation of mass means

Answer 8

Mass of Reactants = Mass of Products
The atoms in a reaction do not change, they only rearrange themselves, so the mass doesnt change .

Question 9

Balance
Magnesium + Oxygen –> Magnesium Oxide

Answer 9

Mg + O2 –> MgO
Mg + O2 –> 2 MgO
2Mg + O2 –> 2 MgO