Part IV Acids and Bases

Solution X contains 100 cm³ of 1.0 M CH₃COOH(aq). Which of the following statements concerning solution X is correct?

• A. It does not contain OH^–(aq).

• B. Less than 0.10 mol of NaOH(aq) is needed to completely neutralize solution X.

• C. It reacts with NH₃(aq) to give salt and water only.

• D. It has a pH value of 0.

300.0 cm³ of 0.50 mol dm^–3 Na₂SO₄(aq) is mixed with 100.0 cm³ of 1.0 mol dm^–3 CaCl₂(aq). What is the concentration of SO₄^2–(aq) in the resultant mixture?

• A. 0.125 mol dm^–3

• B. 0.250 mol dm^–3

• C. 0.375 mol dm^–3

• D. 0.500 mol dm^–3

Which of the following statements about the four solutions is correct?

• A. The pH values of R and S are the same.

• B. When mixing Q and R, HCl is in excess.

• C. The pH value of Q is greater than that of P.

• D. When mixing P and R, a neutral solution is produced.

Which of the following substances, when mixed with dilute sulphuric acid, can be used to prepare barium sulphate?

• A. Barium

• B. Barium oxide

• C. Barium chloride

• D. Barium carbonate

The pH of a sample of nitric acid is 3.0. 200.0 cm³ of the sample is diluted to 400.0 cm³ by adding distilled water. What is the pH of the resultant solution?

• A. 1.5

• B. 2.7

• C. 3.3

• D. 6.0

When an aqueous solution of Y is heated with NaOH(aq), an alkaline gas forms. When an aqueous solution of Y is added to acidified AgNO₃(aq), there is no observable change. Which of the following compounds might Y be?

• A. KCl

• B. Ca(NO₃)₂

• C. NH₄Cl

• D. NH₄NO₃

5.1 g of potassium hydrogenphthalate (C₈H₅O₄K) is dissolved completely in distilled water and the solution is made up to 250.0 cm³. 25.0 cm³ of the potassium hydrogenphthalate solution is titrated against 0.15 M sodium hydroxide solution.

What is the volume of sodium hydroxide solution needed for complete reaction?

(Molar mass of C₈H₅O₄K = 204.1 g mol^–1)

• A. 16.7 cm³

• B. 25.0 cm³

• C. 33.4 cm³

• D. 37.5 cm³

A sample of concentrated sodium chloride solution has a density of 1.29 g cm^–3 and contains 22.6% of sodium chloride by mass. What is the concentration of sodium chloride in the sample?

(Relative atomic masses: Na = 23.0, Cl = 35.5)

• A. 4.99 mol dm^–3

• B. 8.22 mol dm^–3

• C. 12.8 mol dm^–3

• D. 22.1 mol dm^–3

7.40 g of solid acid X is dissolved in distilled water and made up to 250.0 cm³ of solution. 25.0 cm³ of the solution requires 23.50 cm³ of 0.50 M NaOH(aq) for complete neutralization. What is the basicity of X?

(Molar mass of X = 126.0 g mol^–1)

• A. 1

• B. 2

• C. 3

• D. 4

An acid-alkali titration is performed using the set-up as shown.

Which of the following statements concerning the titration is INCORRECT?

• A. The temperature of the mixture increases.

• B. The pH of the mixture decreases.

• C. At the end point, the mixture changes from colourless to very pale pink.

• D. The concentration of Na⁺(aq) ions of the mixture decreases.