Chemical Reactions
Chemical Reactions
A chemical reaction is when a ___ substance
has been made. The chemicals that react are
called ________. A chemical reaction may
have occurred if there is a colour ______, a
change in __________ or if _____ is observed
( this is because a ___ is produced).
reactants
gas
change
temperature
fizzing
new
Chemical or Physical
Rusting
Chemical
Ice melting
Physical
Adding water to
orange squash
Physical
Burning natural gas
Chemical
Making glass
Chemical
Candle wax melting
Physical
Types of chemical reactions
• Neutralisation
• Thermal decomposition
• Precipitation
• Oxidation
• Reduction
• Displacement
• Exothermic
• Endothermic
Precipitation
• This is where two solutions are mixed and
a solid which does not dissolve in water is
produced
Lead nitrate (aq) + Sodium iodide (aq)
Lead iodide (s) + Sodium nitrate (aq)
Formation of lead iodide
Thermal Decomposition
• Thermal decomposition is a reaction where
heat breaks down a chemical into smaller
parts
Limestone
Calcium
carbonate
HEAT
Lime
HEAT
Calcium
oxide
Thermal decomposition
Practical to show the thermal
decomposition of copper
carbonate
Neutralisation
• Neutralisation is a reaction between an
acid and an alkali. It forms a neutral
solution
Hydrochloric acid + sodium hydroxide
Sodium chloride + water
Oxidation reactions
• Oxidation is a reaction where oxygen is
gained
Sulphur + oxygen
Sulphur
Oxygen Oxygen
Sulphur dioxide
Reduction reactions
• A reduction reaction is when oxygen is lost
in a reaction
Copper oxide
Copper
Copper Oxygen
Displacement Reaction
• This is where a more reactive element
displaces a less reactive element from its
compound
Iron + copper sulphate
Iron + copper sulphate
Displacement reaction
Endothermic and exothermic
• An exothermic reaction is a reaction which
gives out heat energy
• An endothermic reaction is a reaction
which takes in heat energy