Question

1.)

Which of the following aqueous solutions are good buffer systems?
.

0.39 M barium chloride + 0.26 M calcium chloride

0.29 M ammonia + 0.40 M sodium hydroxide

0.11 M calcium hydroxide + 0.20 M calcium bromide

0.24 M hydrobromic acid + 0.24 M sodium bromide

0.13 M acetic acid + 0.17 M sodium acetate

2.)

Which of the following aqueous solutions are good buffer systems?
.

0.11 M potassium hypochlorite + 0.20 M hypochlorous acid

0.38 M hydrocyanic acid + 0.26 M potassium cyanide

0.21 M acetic acid + 0.16 M potassium acetate

0.26 M nitric acid + 0.15 M potassium nitrate

0.27 M ammonium bromide + 0.38 M ammonia

Answer 1

Question 1.

0.13 M acetic acid + 0.17 M sodium acetate

Explanation:

A buffer system should contain a weak acid (or weak base) in combination with the salt of its strong conjugate base (or conjugate acid).

Here, acetic acid (CH₃COOH) is a weak acid and sodium acetate is the salt of its strong conjugate base (CH₃COO^-).

Question 2.

0.11 M potassium hypochlorite + 0.20 M hypochlorous acid

0.38 M hydrocyanic acid + 0.26 M potassium cyanide

0.21 M acetic acid + 0.16 M potassium acetate

0.27 M ammonium bromide + 0.38 M ammonia

Note: Hypochlorous acid (HOCl) is a weak acid and potassium hypochlorite is salt of its strong conjugate base (ClO^-).

Hydrocyanic acid (HCN) is a weak acid and potassium cyanide is the salt of its strong conjugate base (CN^-).

acetic acid (CH₃COOH) is a weak acid and potassium acetate is the salt of its strong conjugate base (CH₃COO^-).

Ammonia (NH₃) is a weak base and ammonium bromide is the salt of its strong conjugate acid (NH₄⁺).