YEAR 11 CHEMISTRY: ACIDS AND BASES TEST
NAME:
SECTION A (Multiple Choice) 10 marks in total
Q1. The conjugate base of the species HPO42-(aq) is
A. H3PO4(aq) C. H2PO4-(aq)
B. PO43-(aq) D. HPO32-(aq)
Q2. When hydrogen chloride gas dissolves in excess water, the species least likely to be present is
A. H20(l) C. Cl-(aq)
B. HCl(aq) D. H3O+ (aq)
Q3. Consider the reactions represented by the following equations:
HPO42-(aq) + NH4+(aq) ® NH3(aq) + H2PO4-(aq)
HCO3-(aq) + OH-(aq) ® CO32-(aq) + H2O(l)
HPO42-(aq) + CN-(aq) ® HCN(aq) + PO43-(aq)
HCO3-(aq) + H3O+(aq) ® 2H2O(l) + CO2(g)
In these reactions, which of the following reacts as an amphiprotic (amphoteric) species?
A. HPO42-(aq) C. CO32-(aq)
B. NH4+(aq) D. H2PO4-(aq)
Q4. A solution with a pH of 8 has
A. a higher concentration of hydrogen ions than hydroxide ions
B. a lower concentration of hydrogen ions than hydroxide ions
C. the same concentration of hydrogen ions as hydroxide ions
D. there is insufficient information to determine their concentrations
Q5. A Brönsted acid is defined as:
A. an electron acceptor
B. an electron donor
C. a proton acceptor
D. a proton donor
Q6. Nitric acid can be prepared from the reaction of concentrated sulfuric acid with sodium nitrate. The reaction can be represented by the ionic equation
NO3-(aq) + H2SO4(l) ® HNO3(l) + HSO4-(aq)
In this reaction the nitrate ion acts as:
A. an oxidant C. an acid
B. a reductant D. a base
Q7. Which of the following best explains what happens when pure sulfuric acid is added to water?
A. The molecules of sulfuric acid and water mix without reacting.
B. The sulfuric acid causes the water to ionise but it remains as H2SO4 molecules in the solution.
C. The sulfuric acid molecules react with water molecules to form ions
D. The ions already present in the sulfuric acid lattice dissociate in water.
Q8. Which one of the following acids is NOT capable of donating more than one proton?
A. H2CO3 C. H2S
C. H3PO4 D. CH3COOH
Q9. The concentration of hydrogen ions in gastric juice (stomach acid) is approximately 0.01M. The pH of gastric juice is
A. 2.0 C. 10-0.01
B. log100.01 D. –2.0
Q10. The hydrogen ion concentration of a bottle of household ammonia is 10-11 M. The hydroxide ion concentration will be
A. 10-11 M C. 10-3 M
B. 10-14 M D. 103 M
SECTION B (Extended answers) 40 marks in total.
Q1. Write out definitions of each of the following terms:
(a) acid
(b) base
(c) polyprotic acid
(d) amphiprotic (amphoteric)
(e) pH
(5 marks)
Q2 (a) Write down the conjugate acid for each of the following bases:
(i) NH3 (ii) HSO4-
(iii) OH- (iv) CH3COO-
(b) Write down the conjugate base for each of the following acids:
(i) H2SO4 (ii) H2O
(iii) HNO3 (iv) HPO42-
(8 x .5 = 4 marks)
Q3. Give two examples of each of the following:
(a) a strong acid (b) a strong base
(c) a weak acid (d) a weak base
(4 marks)
Q4. Calculate the pH of the following solutions:
(a) 0.00010 M HCl (b) 0.05 M H2SO4
(c) 1.0 M NaOH (d) 3.55 x 10-4 M Mg(OH)2
(1 + 1 + 1 + 2 = 5 marks)
Q5. Calculate the [H+] of each of the following solutions:
(a) pH = 3 (b) [OH-] = 0.01 M
(2 marks)
Q6. Write balanced chemical equations, including states, for each of the following:
(a) Hydrochloric acid is added to a solution of sodium hydroxide
(b) Nitric acid is added to calcium carbonate (CaCO3) powder
(c) Solutions of silver nitrate (AgNO3) and sodium chloride are mixed to produce a precipitate of silver chloride
(d) The two stages of ionisation of sulfuric acid with water
(i)
(ii)
(8 marks)
Q7. Write ionic equations for each of the following. You may wish to write a chemical equation first.
(a) The formation of the precipitate barium sulfate from solutions of sodium sulfate (Na2SO4) and barium chloride (BaCl2).
(b) The reaction of hydrochloric acid with potassium hydroxide
(4 marks)
Q8. What volume of water must be added to 50 ml of 18M sulfuric acid to reduce its concentration to 2.0 M?
(2 marks)
Q9. A student was required to determine the percentage by mass of acetic acid in a sample of commercial vinegar. She weighed out precisely 3.043g of vinegar into a conical flask and diluted it with approximately 30ml of deionised water. She added several drops of phenolphthalein indicator to the solution and then titrated it against a 0.098M solution of sodium hydroxide. A titre volume of 22.3 ml of NaOH was required.
The relevant equation for this reaction is shown below:
CH3COOH(aq) + NaOH(aq) ® CH3COONa(aq) + H2O (l)
(a) Use these data to determine the percentage by mass of acetic acid in the vinegar sample.
(b) State TWO possible sources of error in her determination.
(i)
(ii)
(4 + 2 = 6 marks)
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