Chemistry 3 simple chemical reactions

• Conservation of mass


  The total mass of reactants is equal to the total mass of products
• Oxidation reaction


  Substance reacts with oxygen in the air
• When a substance has reacted with oxygen it increases in mass as it is one of the reactants we just can't measure oxygen
• The mass increase because the copper reacted with oxygen to create copper oxide as we did not measure the gas it appears to increase when instead the mass of oxygen has just been added to it
• Oxidation reaction


  Reaction where a substance reacts with oxygen
• Combustion reaction


  Oxidation reaction where a fuel is heated and reacts with oxygen to release heat and light energy
• Oxidation reactions


  • Sodium + oxygen → Sodium oxide
  • Iron + oxygen → iron oxide
  • Sulphur + oxygen → sulphur dioxide
  • copper + oxygen → copper oxide
  • Carbon + oxygen → carbon dioxide
• Combustion


  Reacting with oxygen to create a new compound (an oxide), also releasing heat and light
• Hydrocarbon


  Compound made up only of carbon and hydrogen
• Hydrocarbons


  • Wax
  • Petrol
  • Meat hand gas
• Anhydrous copper sulphate


  Chemical test for water - turns from white to blue in the presence of water
• Lime water


  Chemical test for carbon dioxide - turns from clear to cloudy in the presence of carbon dioxide
• Combustion of hydrocarbons


  Hydrocarbon + oxygen → water + carbon dioxide
• Wax is a hydrocarbon, meaning it contains carbon and hydrogen
• Independent variable


  The variable being changed during the experiment
• Dependent variable


  The variable being tested or measured during the experiment
• Controlled variables


  Other variables that must be controlled so they don't affect the independent variable
• A flame needs oxygen to burn so the more oxygen a candle has the longer it takes to burn out
• Fire triangle


  Contains oxygen, fuel and heat
• 26% of oxygen in the air
• If one of the components of the fire triangle were to be removed the fire would be put out
• Thermal decomposition


  Breaking up of larger compounds into smaller compounds under the action of heat
• Thermal decomposition is endothermic, as it requires heat
• Thermal decomposition of metal carbonate

  metal carbonate→ metal oxide + carbon dioxide
• In thermal decomposition the mass would change due to the breaking down of the compound and releasing of carbon dioxide
• Exothermic reaction


  Chemical reaction that releases energy in the form of heat
• Endothermic reaction


  Chemical reaction that absorbs energy from its surroundings in the form of heat
• Thermal reactions


  Chemical reactions that involve the transfer or exchange of heat energy