Acid-Base Equilibrium Systems Test

1.  A concentrated weak acid is best described as which of the following?

2.  According to the BrØnsted-Lowry theory of acids and bases, the anion present in baking soda is a(n)

3.  Hydrogen cyanide, HCN(l), is a pale blue, highly volatile liquid. It exists as gas above 26^oC. It reacts with water to form H₃O⁺(aq) and CN^–(aq).

Which of the following pairs are conjugate acid base pairs of the reaction of hydrogen cyanide, HCN(l) with water?

 4.  Which of the following statements is correct?

5.  A precipitate of zinc hydroxide sits at the bottom of a test tube of distilled water. If the Ksp of this substance is 3.0 x 10^-16, the [Zn] in this solution in mol/L is which of the following?

6.  The Ksp expression for lead(II) bromide is Ksp =

7.  The Ksp for a substance AB₃ is 7.8 x 10^-10. The [B] is which of the following?

8.  Which of the following salts act like acids when applied to the soil?

9.  Which of the following salts act like bases when applied to the soil?

10.  A solution which conducts electricity is a(n)

11.  If a pH meter was placed in a 1.4 mol/L solution of nitric acid the reading would be which of the following?

12.  A small amount of HCl(aq) is added to this buffer system

NO₃^1- +  H₂O  ⇔  OH^1- +  HNO₃

Which one of the following statements is true?

13.  K_w is which of the following?

14.  For phosphoric acid, H₃PO₄, the K_a1 =

I.    [PO₄^3-][H¹⁺]³ / [H₃PO₄]

II.   [HPO₄^2-][H¹⁺] / [H₃PO₄]

III.  [H₂PO₄^1-][H¹⁺] / [H₃PO₄]

IV.  [H₃PO₄] / [H₂PO₄^1-][H¹⁺]

V.  [H₃PO₄] / [PO₄^3-][H¹⁺]³

15.  A solution of nitrous acid has a pH of 2.45. The [H¹⁺] in mol/L and pOH must be respectively

16.  A solution of aluminum chloride has a pH of 6.126. The [OH^1-] in mol/L must be which of the following?

17.  If the K_a of a weak acid is 1.6 x 10^-8, the K_b of its conjugate base partner must be which of the following?

18.  While performing a titration in the laboratory, a student plotted the following graph:

The graph plotted belongs to a titration between

19.  Examine the graph below to answer the next question. 

The graph plotted above belongs to the titration between

20.  Which of the following species is neither an acid or a base as defined by Bronsted-Lowry?

21.  The following data were obtained:

Acids                    K_a

1.  A(aq)              6.2 x 10^–10

2.  B(aq)              6.3 x 10^–4

3.  C(aq)              1.8 x 10^–5

4.  D(aq)              6.3 x 10^–5

From highest ion concentration to lowest, the acids are  _____, _____, _____, and _____. Explain your answer.

22.  Explain why the pH of a buffer solution resists change.

23.  Hydrogen cyanide has the chemical formula HCN. The compound occurs as a colourless gas or a pale blue liquid. Its solution in water is called hydrocyanic acid. It reacts with water as per the following reaction:

HCN(aq) ⁺ H₂O(l) →  CN^–-(aq) + H₃O⁺(aq)

What is the pH of 0.20 mol/L solution of the above acid (K_a = 6.2 ´10^-10)?

24.  A weak acid with a concentration of 0.53 mol/L has a percent ionization of 0.062 %. What is the pH of this weak acid?

25.  Calculate the pH of a buffered solution that is 1.00 M HNO₂ and 1.00 M NaNO₂.  Next calculate the pH after 0.10 mol of NaOH are added to this buffered solution.  (Show your work to get full credit).

26.  Consider a solution that contains both C₅H₅N and C₅H₅NHNO₃. The K_b = 1.7 x 10^-9.  Calculate the ratio [C₅H₅N]/[C₅H₅NH⁺] if the solution has a pH of 4.50.