Soluble salts are formed by reacting metal oxides with acids.
Give one other type of substance that can react with an acid to form a soluble salt.
[1 marks]
ANSWER
Substance(s) that can react with an acid to form a soluble salt are
Metal
(Metal) hydroxide
(Metal) carbonate
Learning Tip
Metal/Metal Hydroxide/Metal Carbonate
Reaction
Remarks
Metal + Acid
Magnesium
Mg
MgCl2 + H2
MgCl2 (Salt)
Metal Hydroxide + Acid
Sodium hydroxide
NaOH
NaCl + H2O
NaCl (Salt)
Metal Carbonate + Acid
Zinc carbonate
ZnCO3
ZnCl2+ H2O + CO2
ZnCl2 (Salt)
Please note that acid can be H2SO4 & HNO3
Calcium nitrate contains the ions Ca2+ and NO3
Give the formula of calcium nitrate.
[1 mark]
ANSWER
The formula of calcium nitrate Ca(NO3)2
Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and a dilute acid.
[6 marks]
ANSWER
The reactants to be used are Magnesium oxide and Sulfuric acid. Following steps to be adopted to achieve pure, dry crystals of Magnesium sulfate:
First step is to add sulfuric acid to a beaker and warm it;
Then add magnesium oxide;
stir the solution well;
Keep adding the magnesium oxide until it becomes in excess;
Use filter paper and funnel to remove excess magnesium oxide;
Heat the solution in an evaporating basin to crystallisation point and leave it to crystallize;
Pat dry with filter paper.
