Question

Could I have the explanations for the respective questions?

Use these answers for questions 8 - 10.

(A) a solution with a pH less than 7 that is not a buffer solution

(B) a buffer solution with a pH between 4 and 7

(C) a buffer solution with a pH between 7 and 10

D) a solution with a pH greater than 7 that is not a buffer solution

(E) a solution with a pH of 7

Ionization Constants

CH3COOH = 1.8 × 10- 5 NH3 = 1.8 × 10-5 H2CO3; K1= 4 ×10-7 H2CO3; K2 = 4 × 10-11 8.

8.A solution prepared to be initially 1 M in NaCl and 1 M in HCl.

9. A solution prepared to be initially 1 M in Na2CO3 and 1 M in CH3COONa

10. A solution prepared to be initially 0.5 M in CH3COOH and 1 M in CH3COONa

Answers: A,D,B

Answer 1

(B) A strong acid as HCl when reacted with a lower amount of a weak base would result in a solution with pH less than 7, but its not a buffer solution as we would have an excess of HCl present in solution. Thus the overall pH of solution would be acidic, pH < 7.

(B) Again mixing a strong acid with a weak base would result in a buffer with pH 4-7. Say for example acid be 1 M HCl and base be 5 M NH3 would result in a buffer with pH < 7 but in the range of 4-7. Like the example 10 below.

(D) A mixture of weak acid and strong base would result in a solution with pH > 7. So mixing equal volumes and concentrations of weak acid and strong base would give such an solution.

(E) A solution of equal concentrations of strong acid and strong base would give a solution with pH = 7. Like the solution 8 below.

8. Overall pH of this solution = -log(1) + 7 = 7, is not a buffer

pH of NaCl would be 7 and that due to HCl would be 0.

9. Overall pH of this solution = 9.37 but is not a buffer

10. Overall pH of this colution = 4.74 + log(1/0.5) = 5.04