Question

Solution of sodium carbonate, potassium chloride, and ammonium sulfate are taken in separate beakers. Dip a litmus paper (red, blue) in each beaker.

Salt	Colour of the litmus paper	Nature of the substance
A
B
C

Answer 1

Salt	Colour of the litmus paper	Nature of the substance
A	Red litmus turns	Basic
B	No color change	Neutral
C	Blue litmus turns to red	Acidic

(i) Observe the color change of litmus paper and tabulate. 

(ii) Name the acid and alkali that react to form each salt given above? 

(iii) Can you explain the color change of the litmus paper on the basis of the nature of the acid and alkali that react to form the salt?

(hint: Potassium chloride is a salt formed by the reaction between a strong acid and a strong alkali)

(i) Salts formed by the reaction between a strong acid and a strong base will be neutral in nature,

eg: KCI 

(ii) Salts formed by the reaction between a strong base and weak acid will be slightly basic 

eg: Na₂CO₃ 

(iii) Salts formed by the reaction between a weak base and strong acid will be slightly acidic

eg:(NH₄)₂SO₄