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SCIPAD - BIG IDEAS - BOOK 2
BASIS OF CHEMICAL REACTIONS
Chemical Equations Recap
Chemical reactions (in which a chemical change occurs) can be represented by word equations.
• The substance(s) that are reacting together are called the reactants.
• The substance(s) produced are called the products.
• An arrow shows the direction of the reaction.
Reactant + reactant product(s)
For example, if magnesium reacts with oxygen to form magnesium oxide, we would write the
word equation as:
Magnesium + oxygen magnesium oxide
1. In the reaction shown above, what are the names of:
(a) the products? 
(b) the reactants? 
2. What does the arrow mean in a word equation? 

3. What happens to the magnesium and the oxygen atoms? Where do they go? 

4. Write the following reactions as word equations. Remember to use ‘+’ instead of ‘reacts with’
or ‘and’. Also remember to use an arrow to show the direction of the chemical change.
(a) Hydrogen reacts with oxygen to form water.
		
(b) Potassium reacts with hydrochloric acid to form potassium chloride and hydrogen.
		
(c) Copper reacts with oxygen to form copper oxide.
		
(d) Hydrogen reacts with oxygen to form water.
		
(e) Lead reacts with oxygen to form lead oxide.
		
(f) Calcium carbonate decomposes to form calcium oxide and carbon dioxide.
		
(g) Nitrogen reacts with oxygen to form nitrogen dioxide.
		
(h) Magnesium reacts with sulfuric acid to form magnesium sulfate and hydrogen.
		
(i) Aluminium forms aluminium oxide when it reacts with oxygen.
			
(j) Calcium oxide is produced when calcium burns in oxygen.
		
(k) Lithium chloride and hydrogen form when lithium and hydrochloric acid react.
			
(l) Sodium hydroxide reacts with nitric acid. Sodium nitrate and water are formed.
		
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