(a) What is the difference between displacement and double displacement reactions? Write equations for these reactions.
(b) What do you mean by a precipitation reaction? Explain giving an example.
(a) Those reactions in which one element takes the place of another element in a compound, are known as displacement reactions.
Equation: CuSO4 (aq) + Zn (s) → ZnSO4 + Cu
Those reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions.
Equation: AgNO3 (aq) + NaCl (aq) → AgCl (s)+ NaNO3 (aq)
(b) Any reaction in which an insoluble solid (called precipitate) is formed that separates from the solution is called a precipitation reaction.
Example: The reaction between barium chloride and sodium sulphate solution to form a white barium sulphate precipitate (along with sodium chloride solution) is an example of a precipitation reaction.
BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)