Question

Which of the following solutions is a good buffer system?

A. a solution that is 0.10 M HI and 0.10 M NH4+
B. a solution that is 0.10 M NaOH and 0.10 M KOH
C. a solution that is 0.10 M HC2H3O2 and 0.10 M LiC2H3O2
D. a solution that is 0.10 M HBr and 0.10 M KC2H3O2

Answer 1

Answer: C) A solution that is 0.10 M
`HC_2H_3O_2` and 0.10 M
`LiC_2H_3O_2` .

Explanation: A buffer solution is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid.

Choice A has equal concentrations(0.10M) of HI and ammonium ion but its not a buffer solution since it has strong acid HI and ammonium ion is also a weak acid.

Choice B has equal concentrations(0.10M) of a NaOH(strong base) and KOH(strong base). Both are strong bases and so its not a buffer solution.

Choice D also has equal concentrations(0.10M) of HBr and potassium acetate. HBr is a strong acid and so this solution is not a buffer solution.

Only choice C is correct as it has acetic acid(weak acid) and a salt (potassium acetate) of its conjugate base.