W Richards The Weald School 22/05/2019 Using Chemistry W Richards The Weald School

Fuels 22/05/2019 A “fuel” is something that can be burned to release heat and light energy. The main examples are: Although these fuels look different, they all contain CARBON and HYDROGEN

Burning Fuels Lots of oxygen: Some oxygen: Little oxygen: Methane 22/05/2019 C H O O H C O Lots of oxygen: Methane Oxygen + Carbon dioxide Water + Water + O H Methane C H Oxygen + O C O Some oxygen: Carbon monoxide O H Water + C H Methane Little oxygen: O Oxygen + C Carbon

Burning Hydrogen Recall the test for hydrogen: The reaction: 22/05/2019 Recall the test for hydrogen: “POP” The reaction: O H Notice that no carbon dioxide or carbon monoxide is produced! H O Hydrogen Oxygen + Water

Energy from Displacement Reactions 22/05/2019 Increasing reactivity Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Lead Copper Silver Gold In previous work we considered the reactivity series: We also looked at displacement reactions, where a more reactive metal will displace a less reactive one from one of its compounds.

Energy from Displacement Reactions 22/05/2019 Lots of energy Example 1 – Magnesium and copper sulphate O Cu S Copper sulphate + Mg O S Magnesium sulphate + Cu Copper Mg Magnesium Some energy Example 2 – Zinc and copper sulphate Zn O Cu S Zinc + Copper sulphate Copper Zinc sulphate

Electrical energy from differences in reactivity 22/05/2019 Zinc rod Copper rod Filter paper soaked in potassium nitrate V Zinc sulphate Copper sulphate The bigger the difference in reactivity, the bigger the voltage

Conservation of mass in reactions 22/05/2019 In any reaction the total mass of products is the same as the total mass of the reactants Example 1 – Magnesium oxide and hydrochloric acid Mg O H Cl 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms Also 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms Example 2 – Burning methane C H O