Download Topic 1 Chemical Reactions What is a chemical

Topic 1
Chemical Reactions
What is a chemical reaction?
• A chemical reaction can be defined as
the process in which changes occur in
matter to produce new substances.
• These chemical changes happen all
around us.
Everyday Chemical Reactions
• Cars rusting
• Frying an egg
• Coal burning
• Manufacture of medicines
• Digestion of our food
In a chemical reaction a new substance is
always formed.
• The starting chemicals in reactions are
called reactants and the new substances
formed are called products.
Reactants  Products
Signs of a chemical reaction are:
•
•
•
•
A colour change
The appearance of a solid (precipitate)
A fizzing as a gas forms (effervescence)
A temperature change
1. Precipitation Reaction
Aim: To investigate what happens when
sodium carbonate solution is added to
cobalt (II) chloride solution.
Method:
+
5ml sodium
carbonate
solution
5ml cobalt
chloride
solution
Result:
Conclusion: On adding two solutions
together, a solid may be formed. This is
called precipitation.
Precipitation is the reaction in which a
precipitate is formed.
Precipitate When two liquids are mixed an
insoluble solid that appears is called a
precipitate.
See pg 5 of data booklet