Types of Chemical Reaction
Starter: in pairs brainstorm as many different
TYPES of reaction as you know
Neutralisation
This is the type of reaction that occurs
when an ACID is mixed with an ALKALI to
produce a NEUTRAL solution.
ACID + ALKALI
SALT + WATER
Can you think of 3 examples of neutralisation
reactions?
Extension – when can knowing about
neutralisation reactions be useful?
Neutralisation
A use of neutralisation is in the treatment
of indigestion. The acid in the stomach is
hydrochloric acid (HCl)
Word
Equation
Hydrochloric + Magnesium
Acid
Carbonate
HCl
+ MgCO3
Symbol
Equation
Magnesium + Water
Chloride
MgCl2 + H2O
What do these large
numbers stand for?
Measuring the strength of an
acid or alkali
Not all acids/alkalis are the same strength,
so we use the pH scale to explain it
A neutral pH means there is no acid or alkali
present. Neutral pH is 7.
Adding an alkali to an acid brings its pH
closer to 7.
A neutral pH means there is no acid or alkali
present. Neutral pH is 7.
Adding an acid to an alkali brings its pH
closer to 7.
You have 3 antacids, their pHs are:
• Antacid A – pH 9
• Antacid B – pH 13
• Antacid C – pH 10.5
Which of these will be better at neutralising
the Hydrochloric Acid if you have to use the
same amount of each?
The extremes of the pH scale are very
harmful to human beings. Which antacids do
you think you should rule out using because
of this?
You have 3 antacids, the mass required to
fully neutralise stomach acid is:
• Antacid A – 84g
• Antacid B – 50g
• Antacid C – 70g
The cost per 100g is:
• Antacid A – 67p
• Antacid B – 98p
• Antacid C – 59p
Which of these is the most cost effective?
What factors will affect the RRP of the
antacid?
Oxidation
This is the type of reaction that occurs
when a metal is combined with oxygen to
form a metal oxide.
METAL + OXYGEN
METAL OXIDE
What is the most common type of oxidation
reaction?
Oxidation
Oxidation is the process behind the
rusting of iron. It weakens nails, bikes and
other metal objects as the metal oxide is
not as strong
Iron + Oxygen
2Fe +
3O2
What do these large
numbers stand for?
Iron Oxide
2Fe2O3
Combustion
This is the type of reaction that occurs
when a fuel is combined with oxygen to
produce water and carbon dioxide
releasing energy
FUEL + OXYGEN
CARBON + WATER
DIOXIDE
What do we use combustion reactions for?
Extension – what biological combustion
reaction have we studied?
Combustion
Combustion is used to power cars, buses,
aeroplanes etc. The fuel is petrol, whose
chemical name is octane
Octane + Oxygen
C8H18
+ O2
Carbon + Water
Dioxide
CO2 + H2O
Is there the same amount of each
element on either side of the arrow?
Combustion
When we write symbol equations we have
to make sure that they are BALANCED i.e.
That there is the same number of each
element on either side of the arrow.
C8H18 + O2
2C8H18 + 27O2
CO2 +
H2O
16CO2 + 18H2O
Don’t panic!
I will show you how to balance equations next
week.
Decomposition
This is the type of reaction that occurs
when an large compound is broken down
into smaller compounds
Compound 1
Compound 2 + Compound 3
Can you think of any examples of
decomposition reactions?
Decomposition
An example of decomposition is the
fermentation of glucose to form ethanol
and carbon dioxide
Word
Equation
Glucose
C6H12O6
Ethanol + Carbon Dioxide
2C2H5OH +
2CO2
When is this reaction used?
Symbol
Equation
Thermal Decomposition
An example of thermal decomposition is
the breakdown of calcium carbonate into
calcium oxide and carbon dioxide
Calcium Carbonate
Calcium
Oxide
+
Carbon
Dioxide
Try to write the symbol equation using the
periodic table to help
CaCO3
CaO
+
CO2
Displacement
This is the type of reaction that occurs
when a more reactive element takes the
place of a less reactive one in a
compound
Compound + Element
1
2
Compound + Element
2
1
Can you think of any examples of
displacement reactions?
Displacement
An example of displacement is the
decolourisation of copper sulphate (blue)
by zinc
Word
Equation
Copper
Sulphate
+
Zinc
Zinc +
Sulphate
Copper
Try to write the symbol equation using the periodic
table to help. The symbol for sulphate is SO4
CuSO4
+
Zn
ZnSO4 +
Cu
Metals and Acid
This is the type of reaction that occurs
when a metal reacts with an acid to form a
salt and hydrogen gas
METAL + ACID
SALT
+ HYDROGEN
What is a test for hydrogen gas?
Metals and Acid
An example of this type of reaction occurs
when magnesium is placed in sulphuric
acid
Magnesium + Sulphuric
Acid
Magnesium + Hydrogen
Sulphate
Try to write the symbol equation using the periodic
table to help. The symbol for sulphate is SO4
Mg
+
H2SO4
MgSO4
+
H2