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1. Calcium carbonate and dilute hydrochloric acid
ACID + CARBONATE ⇒ SALT + WATER + CARBON DIOXIDE
Effervescence is easy to see here as the colourless gas, carbon dioxide, is produced. The solid carbonate is dissolving, but the reaction is too slow to see this happening.
|
FULL |
CaCO3(s) + 2HCl(aq) ® CaCl2(aq) + H2O(l) + CO2(g) |
|
IONIC |
CaCO3(s) + 2H+(aq) ® Ca2+(aq) + H2O(l) + CO2(g) |
2. Copper(II) carbonate and dilute sulfuric acid
ACID + CARBONATE ⇒ SALT + WATER + CARBON DIOXIDE
Again we see effervescence caused by the release of carbon dioxide gas. This time the solid green copper(II) carbonate is seen dissolving although some still remains at the end. The appearance of a blue solution of copper(II) ions is also observed.
|
FULL |
CuCO3(s) + H2SO4(aq) ® CuSO4(aq) + H2O(l) + CO2(g) |
|
IONIC |
CuCO3(s) + 2H+(aq) ® Cu2+(aq) + H2O(l) + CO2(g) |
3. Zinc metal and dilute hydrochloric acid
ACID + METAL ⇒ SALT + HYDROGEN
Effervescence is caused this time by the release of hydrogen gas. The metal is dissolving, but the reaction is too slow to see this happening.
|
FULL |
Zn(s) + 2HCl(aq) ® ZnCl2(aq) + H2(g) |
|
IONIC |
Zn(s) + 2H+(aq) ® Zn2+(aq) + H2(g) |
4. Nickel(II) oxide and dilute nitric acid
ACID + BASE ⇒ SALT + WATER
The black nickel(II) oxide solid is seen dissolving and producing a green solution of nickel(II) ions.
|
FULL |
NiO(s) + 2HNO3(aq) ® Ni(NO3)2(aq) + H2O(l) |
|
IONIC |
NiO(s) + 2H+(aq) ® Ni2+(aq) + H2O(l) |
5. Silver nitrate and potassium chromate solutions
This is a precipitation reaction. Insoluble, orange-red silver chromate solid is produced.
|
FULL |
2AgNO3(aq) + K2CrO4(aq) ® Ag2CrO4(s) + 2KNO3(aq) |
|
IONIC |
2Ag+(aq) + CrO42-(aq) ® Ag2CrO4(s) |
6. Barium chloride and dilute sulfuric acid
This is another precipitation equation. Dilute sulfuric acid is ionised in aqueous solution and produces a white precipitate of barium sulfate.
|
FULL |
BaCl2(aq) + H2SO4(aq) ® BaSO4(s) + 2HCl(aq) |
|
IONIC |
Ba2+(aq) + SO42-(aq) ® BaSO4(s) |
7. Zinc metal and copper(II) sulfate solution
This is a displacement reaction. Zinc is more reactive than copper so displaces it from its salt. We can see the appearance of brown copper metal on the surface of the zinc and the loss of the blue copper(II) colour as it is replaced by the colourless zinc ion.
|
FULL |
Zn(s) + CuSO4(aq) ® ZnSO4(aq) + Cu(s) |
|
IONIC |
Zn(s) + Cu2+(aq) ® Zn2+(aq) + Cu(s) |
8. Copper metal and silver nitrate solution
This is another displacement reaction. Copper is more reactive than silver so displaces it from its salt. We can see the appearance of grey silver metal on the surface of the copper and the appearance of the blue copper(II) colour.
|
FULL |
Cu(s) + 2AgNO3(aq) ® Cu(NO3)2(aq) + 2Ag(s) |
|
IONIC |
Cu(s) + 2Ag+(aq) ® Cu2+(aq) + 2Ag(s) |