Syllabus
(e) redox reactions of metals with acids to form salts, including full equations
(e) redox reactions of metals with acids to form salts, including full equations
In Year 9 you should have learned the general equation:
Metal + Acid → Salt + Water
And you probably learned it along with the neutralisation reactions of Acids and Bases.
But this is not just neutralisation because it also involves changes of Oxidation Number, which makes this a Redox reaction.
For instance,
Calcium + Sulphuric Acid → Calcium Sulphate + Hydrogen
Ca(s) + H2SO4(aq) → CaSO4(aq) + H2(g)
Calcium has gone from an element (Oxidation No.= 0) to a compound (Oxidation No. =+2)
This is Oxidation
Hydrogen has gone from a compound (Oxidation No. = +1) to an element (Oxidation No. = 0)
This is Reduction
The same would be true for any Metal-Acid combination as we can show through Ionic Equations for metals which form 1+, 2+ and 3+ ions respectively.
2M(s) + 2H+(aq) → 2M+(aq) + H2(g)
M(s) + 2H+(aq) → M2+(aq) + H2(g)
M(s) + 3H+(aq) → M3+(aq) + 1.5 H2(g)
That should allow you to write a balanced chemical equation for any combination of Metal & Acid.
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