Question

Which of the following mixture is not a buffer solution?

• A. 100ml of 0.5 $N-C{H}_{3}COOH+$ 100 ml of 0.05 N- NaOH
• B. 100ml of 0.5 $N-N{H}_{4}OH+$ 100ml of 0.5 N-HCl
• C. 100 ml of 0.5 $N-N{H}_{4}OH+$ 10 ml of 0.5 $N-H_{2}S{O}_4.$
• D. 300 ml of 0.5 $N-N{H}_{4}OH+$ 200 ml of 0.5 $N-HN{O}_3$

Answer 1

Answer: (B)

100ml of 0.5 $N-N{H}_{4}OH+$ 100ml of 0.5 N-HCl

Basic buffer solution is prepared by mixing a weak base and its salt with strong acid.
In the mixture containing 100ml of 0.5 N $N{H}_{4}OH$ + 100ml of 0.5 N-HCl, equal number of moles of ammonium hydroxide and hydrochloric acid are present.
They completely neutralize each other to form salt ammonium chloride. Thus weak base ammonium hydroxide is not present in the mixture.
Hence, this mixture is not a buffer solution.