The Acidic Environment HSC Questions
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2008
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2009
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2011
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2009
3 Which of the following groups contains ONLY acidic substances?
9.3.1.2.1
(A) Antacid tablets, baking soda, laundry detergents
(B) Blood, oven cleaner, seawater
(C) Milk, tea, drain cleaner
2007
(D) Vinegar, wine, aspirin
6 Which aqueous solution turns phenolphthalein pink?
9.3.1.2.2
(A) HCl
(B) NaCl
(C) NaOH
2010
(D) CH3OH
3 Which substance shows the correct indicator colour?
9.3.1.2.2
2004
9.3.1.3.1
Question 23 (3 marks)
A natural indicator was made by heating yellow flowers with water. The resulting
yellow solution was tested with a range of substances. The results are recorded below.
Assess the usefulness of the yellow solution as an acid–base indicator.
2011
Question 32 (5 marks)
To determine the pH of garden soil, a sample was first saturated with distilled water in a petri
dish. Barium sulfate powder was added to the surface of the sample, and drops of the three
indicators listed below were added to separate parts of the sample. The colours observed are
shown in the table.
9.3.1.2.3
(b) Using the information given, select the plant that will grow well at the current soil pH, and
justify your selection. (2 marks)
9.3.1.3.1
(c) Outline the method you would use to test a natural indicator that has been prepared in the
school laboratory. (2 marks)
2009
Question 21 (6 marks)
The graph shows changes in pH for the titrations of equal volumes of solutions of two
monoprotic acids, Acid 1 and Acid 2.
9.3.1.3.2
(d) Why would phenolphthalein be a suitable indicator for both titrations? (1 mark)
2006
Question 23 (6 marks)
Correct swimming pool maintenance requires regular monitoring of the pH level of the water.
9.3.1.3.3
(a) Select the best indicator from the graph to check that the pH of swimming pool water lies
within the correct range of 7.0 – 7.6. Justify your choice. (3 marks)
2011
3 Which of the following lists contains ONLY basic substances?
9.3.1.3.3
(A) Oven cleaner, urine, vinegar
(B) Lemonade, drain cleaner, blood
(C) Baking soda, ammonia, sea water
2001
(D) Antacid, dishwashing detergent, lemon juice
6 The graph shows the colour ranges of the acid–base indicators methyl orange, bromothymol
blue and phenolphthalein.
9.3.1
A solution is yellow in methyl orange, blue in bromothymol blue and colourless in
phenolphthalein.
What is the pH range of the solution?
(A) 4.5 to 6.0
(B) 6.0 to 7.5
(C) 7.5 to 8.5
(D) 8.5 to 10.0
2001
9.3.1
7 A group of students produced a red solution by boiling red cabbage leaves in water. When
dilute sodium hydroxide was added to the solution, it turned purple. When dilute hydrochloric
acid was added to the red solution, no colour change occurred.
2002
Which of these substances, when added, is most likely to cause the red solution to change
colour?
(A) Cleaning solution containing ammonia
(B) Concentrated hydrochloric acid
(C) Orange juice
(D) Vinegar
Question 20 (4 marks)
9.3.1
(a) Identify ONE common household base. (1 mark)
9.3.1
(b) A student used indicators to determine whether three colourless solutions were acidic or
basic. The indicators used are shown in the table. (3 marks)
Samples of each solution were tested with the indicators. The colours of the resulting solutions
are shown in the table.
The student concluded that each of the three solutions tested was basic. Assess
the validity of this conclusion. (3 marks)
2003
9.3.1
2006
1 Which of the following is an acid–base indicator?
(A) Methanol
(B) Methyl orange
(C) Methanoic acid
(D) Methyl ethanoate
10 Phosphorus pentoxide reacts with water to form phosphoric acid according to the following
equation. P2O5(s) + 3H2O(l) → 2H3PO4 (aq)
9.3.2.2.1
Phosphoric acid reacts with sodium hydroxide according to the following equation.
H3PO4 (aq) + 3NaOH(aq) → Na3PO4 (aq) + 3H2O(l)
A student reacted 1.42 g of phosphorus pentoxide with excess water.
What volume of 0.30 mol L-1 sodium hydroxide would be required to neutralise all the
phosphoric acid produced?
2004
9.3.2.2.2
2004
(A) 0.067 L
(B) 0.10 L
(C) 0.20 L
(D) 5.0 L
Question 18 (4 marks)
Analyse the relationship between the position of elements in the Periodic Table, and the acid–
base behaviour of their oxides.
10 Phosgene is prepared from the reaction of carbon monoxide and chlorine in the presence of
a catalyst:
9.3.2.2.4
CO(g) + Cl2 (g) ⇌ COCl2 (g) ΔH = –9.93 kJ mol-1
2008
9.3.2.2.4
Which of the following sets of conditions would produce the highest yield of phosgene?
(A) High temperature, high pressure
(B) Low temperature, low pressure
(C) Low temperature, high pressure
(D) High temperature, low pressure
7 Which of the following changes will always shift this equilibrium reaction to the right?
2HI(g) ⇌ H2 (g) + I2 (g) ΔH = –52 kJ
2010
(A) Adding a catalyst
(B) Increasing the pressure
(C) Increasing the temperature
(D) Adding more of the reactant
18 Chromate and dichromate ions form an equilibrium according to the following equation.
9.3.2.2.4
2CrO42-(aq) + 2H+(aq) ⇌ Cr2O72-(aq) + H2O(l)
Which solution would increase the concentration of the chromate ion (CrO42-) when added to
the equilibrium mixture?
(A) Sodium nitrate
(B) Sodium chloride
(C) Sodium acetate
(D) Ammonium chloride
2009
2 Unpolluted rain water in New South Wales is slightly acidic.
9.3.2.2.5
Which substance is the major contributor to this acidity?
(A) Ozone
(B) Sulfur dioxide
(C) Carbon dioxide
(D) Nitrogen dioxide
2011
9.3.2.2.5
2+
13 When chloride ions are added to a solution containing Co(H2O)6 (aq), the following
equilibrium is established.
Which of the following statements about the colour of the solution is true?
2005
(A) Diluting the solution with water will make it turn blue.
(B) If the reaction is exothermic, heating the solution will make it turn blue.
(C) If the reaction is endothermic, cooling the solution will make it turn pink.
(D) Adding a large amount of solid potassium chloride to the solution will make it turn pink.
Question 22 (7 marks)
A student carried out a first-hand investigation to identify the relationship between the mass of
a metal used in a reaction, and the volume of gas produced. The first-hand investigation was
carried out at 25°C, and 100 kPa. In each experiment, 200 mL of hydrochloric acid was added
to some zinc, and the volume of gas produced was recorded. The diagram shows the equipment
used, and the table contains the student’s results.
9.1.12.3c (a) Graph the results from these experiments. (3 marks)
9.3.2.2.9
(b) Predict the volume of gas that would be produced in this experiment if 3.00 g of zinc had
been used. Justify your answer. (2 marks)
9.3.2.2.9
(c) Calculate the theoretical volume of gas produced at 25°C and 100 kPa by the reaction of
0.56 g of zinc with the 200 mL of hydrochloric acid. (2 marks)
2007
Question 22 (7 marks)
The following article was sourced from the internet.
In 2004, Australia’s Minister for the Environment announced that the allowable amounts of sulfur in
unleaded petrol and diesel would be reduced over the next 5years.Currently sulfur in diesel is 500 parts
per million (ppm) but it will be cut to 50ppm on 1 January 2006 and capped at 10 ppm from January 2009.
9.3.2.2.9
(a)Calculate the volume of sulfur dioxide produced when a full tank(capacity60kg) of diesel is
consumed at 25°C and 100kPa in November2007. (3 marks)
2008
2 What are the volumes of one mole of argon, Ar, and one mole of fluorine, F2, at 0°C and 100
kPa?
9.3.2.2.9
2008
Question 20 (3 marks)
1.22 g of an unknown gas has a volume of 15.0 L at 100 kPa and 25°C.
9.3.2.2.9
(a) Calculate the molar mass of the gas. (2 marks)
(b) Identify the gas. (1 mark)
9.3.2.2.9
2010
19 Sodium azide is used in automobile airbags to provide a source of nitrogen gas for rapid
inflation in an accident. The equation shows the production of nitrogen gas from sodium azide.
9.3.2.2.9
2NaN3 (s) → 2Na(s) + 3N2 (g)
2010
9.3.2.2.9
What mass of sodium azide will produce 40 L of N2 at 100 kPa and 0°C?
(A) 70 g
(B) 76 g
(C) 114 g
(D) 172 g
Question 26 (4 marks)
A gas is produced when 10.0 g of zinc is placed in 0.50 L of 0.20 mol L-1 nitric acid. Calculate
the volume of gas produced at 25°C and 100 kPa. Include a balanced chemical equation in
your answer.
2005
9.3.2.3.1
7 A series of observations was made about a first-hand investigation.
• A cup of carbonated soft drink was poured from a newly-opened, chilled bottle.
• A lot of bubbles were observed in the cup.
• The cup was then left on the kitchen bench for several hours.
• After this time, it was observed that there were no bubbles visible in the cup.
Why were there no bubbles visible in the cup after several hours?
2011
(A) The bubbles of carbon dioxide had dissolved into the soft drink.
(B) The carbon dioxide had been neutralised by the water in the soft drink.
(C) Carbon dioxide is less soluble at higher temperatures and lower pressures.
(D) Carbon dioxide is more soluble at higher temperatures and lower pressures.
19 All of the carbon dioxide in a soft drink with an initial mass of 381.04 g was carefully
extracted and collected as a gas. The final mass of the drink was 380.41 g.
9.3.2.3.1
What volume would the carbon dioxide occupy at 100 kPa and 25°C?
2008
(A) 0.33 L
(B) 0.35 L
(C) 0.56 L
(D) 0.63 L
Question 24 (5 marks)
9.3.2.3.9
The table shows four fuels and their various properties.
(c) How many litres of hydrogen gas at 25°C and 100 kPa would be needed to supply the same
amount of energy as 80 L of petrol? (2 marks)
2001
5 The pH of unpolluted rainwater is about 6.0. Which substance contributes most to this?
9.3.2
(A) CO2
(B) N2
(C) NO2
(D) O3
8 The burning of sulfur can be described by the following equation: S(s) + O2 (g) → SO2 (g)
2001
9.3.2
What volume of sulfur dioxide gas will be released at 25°C and 101.3 kPa when 8.00 g of
sulfur is burnt?
(A) 3.06 L
(B) 6.12 L
(C) 12.24 L
(D) 24.47 L
2001
9 An understanding of Le Chatelier’s principle is important in the chemical industry.
9.3.2
Which prediction can be made using this principle?
2001
(A) The identity of products of a chemical reaction
(B) The effect of changes in temperature on the rates of reactions
(C) The effect of catalysts on the position of equilibrium reactions
(D) The effect of changes in the concentration of chemical substances in equilibrium
10 The following equations describe some reactions in the formation of acid rain:
9.3.2
SO2(g) + H2O(l) ⇌ H+(aq) + HSO3-(aq)
2H+(aq) + 2HSO3-(aq) + O2 (g) → 4H+(aq) + 2SO42-(aq)
What would occur if some solid sodium sulfate (Na2SO4) were added to a sample of acid rain?
2002
9.3.2
(A) The amount of SO2 (g) would increase and the acidity of the solution would decrease.
(B) The amount of SO2 (g) would increase and the acidity of the solution would increase.
(C) The amount of SO2 (g) would be unchanged and the acidity of the solution would be
unchanged.
(D) The amount of SO2 (g) would be unchanged and the acidity of the solution would decrease.
Question 21 (7 marks)
Evaluate the impact of industrial sources of sulfur dioxide and nitrogen oxides on the
environment, making use of appropriate chemical equations.
2002
Question 23 (4 marks)
A bottle of soft drink was placed on an electronic balance and weighed. The cap was removed
and placed next to the bottle on the balance. The mass of the cap, bottle and its contents was
monitored. The results are shown in the graph. The experiment was conducted at 25°C and
101.3 kPa. Assume that no evaporation has occurred.
9.3.2
(a) Identify the gas released. (1 mark)
9.3.2
(b) Calculate the volume of the gas released. (3 marks)
2003
7 The diagram is a representation of the Periodic Table. The positions of six different elements
are shown.
9.3.2
What are the reactions of oxides of these elements with acid and with base?
2003
Question 22 (3 marks)
9.3.2
(b) A mass of 72.5 g of ethanol was burnt completely in air. Calculate the volume of carbon
dioxide that was produced at 25°C and 100 kPa. (2 marks)
2006
Question 23 (6 marks)
Correct swimming pool maintenance requires regular monitoring of the pH level of the water.
9.3.3.2.3
(b) Another part of swimming pool maintenance is adjusting chlorine levels in the pool.
‘Liquid chlorine’ is a solution of sodium hypochlorite (NaOCl) which can be used to do this.
Upon addition of sodium hypochlorite to the pool, the following equilibrium reaction occurs:
OCl-(aq) + H2O(l) ⇌ HOCl(aq) + OH-(aq)
(ii) Explain how the addition of sodium hypochlorite will affect the pH of the water in the
pool. (2 marks)
2004
7 The figure shows the pH values of some substances.
9.3.3.2.5
Based on the pH values shown in the figure, which of the following statements about the
concentration of hydrogen ions is correct?
(A) It is twice as great in milk as that in lemon juice.
(B) It is 1 000 000 times greater in soap than in wine.
(C) It is three times greater in wine than in bleach solution.
(D) It is 1 000 times greater in distilled water than in soap.
2007
Question 21 (5 marks)
9.3.3.2.5
(a) State what colour the red cabbage indicator would be in a 0.005 mol L–1 solution of H2SO4.
Show your working. (1 mark)
9.3.3.2.5
(b) Using the red cabbage indicator, what colour would the solution be if 10 mL of 0.005 mol
L–1 H2SO4 was diluted to 100 mL? (1 mark)
2008
14 20 mL of 0.08 mol L–1 HCl is mixed with 30 mL of 0.05 mol L–1 NaOH.
What is the pH of the resultant solution?
9.3.3.2.5
2004
(A) 1.1
(B) 2.7
(C) 4.0
(D) 7.0
Question 24 (5 marks)
The diagram shows three reagent bottles containing acids.
9.3.3.2.5
(a) Calculate the pH after 10.0 mL of 0.01 mol L-1 hydrochloric acid solution is diluted by the
addition of 90.0 mL of distilled water. (1 mark)
9.3.3.2.6
(c) Explain the difference in pH between the three acids in the diagram. (2 marks)
2006
8 Acid X is 0.1 mol L–1 hydrochloric acid. Acid Y is 1.0 mol L–1 acetic acid (ethanoic acid).
9.3.3.2.6
How does acid X compare with acid Y?
(A) X is weaker and more dilute than Y.
(B) X is stronger and more dilute than Y.
(C) X is weaker and more concentrated than Y.
(D) X is stronger and more concentrated than Y.
2007
8 Acid X and acid Y are both monoprotic weak acids of equal concentration. Acid X is a
stronger acid than acid Y.
9.3.3.2.6
Which statement about acid X and acid Y is correct?
2010
(A) Acid Y is completely ionised in solution.
(B) The solution of acid X is less ionised than the solution of acid Y.
(C) The solution of acid X has a lower pH than the solution of acid Y.
(D) 1 mole of acid Y requires a greater volume of 1.0 mol L–1 NaOH for neutralisation than 1
mole of acid X.
7 Equal volumes of four 0.1 mol L-1 acids were titrated with the same sodium hydroxide
solution.
9.3.3.2.6
Which one requires the greatest volume of base to change the colour of the indicator?
2010
9.3.3.2.7
(A) Citric acid
(B) Acetic acid
(C) Sulfuric acid
(D) Hydrochloric acid
Question 21 (3 marks)
A 0.001 mol L-1 solution of hydrochloric acid and a 0.056 mol L-1 solution of ethanoic acid
both have a pH of 3.0.
Why do both solutions have the same pH?
2004
Question 24 (5 marks)
9.3.3.3.5
(b) Explain the use of acetic acid and citric acid as food additives. (2 marks)
2005
8 What would be the pH of a 0.1 mol L-1 solution of sulfuric acid?
9.3.3.3.7
2006
(A) Less than 1.0
(B) Exactly 1.0
(C) Between 1.0 and 7.0
(D) Greater than 7.0
Question 17 (4 marks)
9.3.3.3.7
(a) Calculate the pH of a 0.2 mol L–1 solution of hydrochloric acid. (1 mark)
9.3.3.3.7
(b) Calculate the pH after 20 mL of 0.01 mol L–1 sodium hydroxide is added to 50 mL of 0.2
mol L–1 hydrochloric acid. Include a balanced chemical equation in your answer. (3 marks)
2007
10 A 0.1 mol L–1 HCl solution has a pH of 1.0.
9.3.3.3.7
What volume of water must be added to 90 mL of this solution to obtain a final pH of 2.0?
(A) 10 mL
(B) 180 mL
(C) 810 mL
(D) 900 mL
Question 21 (6 marks)
2009
9.3.3.3.7
The graph shows changes in pH for the titrations of equal volumes of solutions of two
monoprotic acids, Acid 1 and Acid 2.
(c) Calculate the concentration of hydrogen ions when 20 mL of KOH(aq) has been added to
Acid 1. (1 mark)
2001
9.3.3
Question 20 (4 marks)
A 0.1 mol L–1 solution of hydrochloric acid has a pH of 1.0, whereas a 0.1 mol L–1 solution of
citric acid has a pH of 1.6.
(a) State ONE way in which pH can be measured. (1 mark)
(b) Explain why the two solutions have different pH values. (3 marks)
2003
8 A sulfuric acid solution has a concentration of 5 x 10-4 mol L-1.
What is the pH of this solution, assuming the acid is completely ionised?
9.3.3
(A) 3.0
(B) 3.3
(C) 3.6
(D) 4.0
2002
9.3.3
Question 22 (5 marks)
Solutions of hydrochloric acid, acetic acid and sulfuric acid were prepared. Each of the
solutions had the same concentration (0.01 mol L–1). The pH of the acetic acid solution was
3.4.
(a) Calculate the pH of the hydrochloric acid solution. (1 mark)
9.3.3
(b) Compare the pH of the sulfuric acid solution to the pH of the hydrochloric acid solution.
Justify your answer. (No calculations are necessary.) (2 marks)
9.3.3
(c) Explain why the acetic acid solution has a higher pH than the hydrochloric acid solution. (2
marks)
2004
5 Which statement best represents Davy’s definition of an acid?
9.3.4.2.1
(A) Acids contain oxygen.
(B) Acids are proton donors.
(C) Acids contain replaceable hydrogen.
(D) Acids ionise in solution to form hydrogen ions.
8 According to the Arrhenius theory of acids and bases, an acid is a substance that
2008
9.3.4.2.1
2010
(A) tastes sour.
(B) is capable of donating a hydrogen ion.
(C) can accept a pair of electrons to form a co-ordinate covalent bond.
(D) increases the concentration of hydrogen ions in an aqueous solution.
8 In a research report a student wrote, ‘Acids are compounds that contain hydrogen and can
dissolve in water to release hydrogen ions into solution.’
9.3.4.2.1
Who originally stated this theory of acids?
2007
9.3.4.2.4
(A) Arrhenius
(B) Brönsted–Lowry
(C) Davy
(D) Lavoisier
9 Which of the following aqueous solutions has a pH greater than 7?
(A) Sodium citrate
(B) Sodium chloride
(C) Ammonium nitrate
(D) Ammonium chloride
2008
Question 27 (4 marks)
9.3.4.2.4
(a) Classify these salts as forming acidic, basic or neutral solutions. (3 marks)
9.3.4.2.4
(b) From the table, choose a salt that forms an acidic or basic solution, and justify its
classification. Include an equation to illustrate your answer. (1 mark)
2009
7 What is the conjugate base of HSO4-?
9.3.4.2.5
(A) SO32(B) SO42(C) H2SO4
(D) HSO3Question 22 (3 marks)
(a) Define the term amphiprotic. (1 mark)
2004
9.3.4.2.6
9.3.4.2.6
(b) Write TWO chemical equations to show that the dihydrogen phosphate ion (H2PO4- ) is
amphiprotic. (2 marks)
2005
10 A titration was conducted by adding NaOH from a teflon-coated burette to HCl in a conical
flask. The pH in the flask was recorded during the titration and Curve A was produced.
9.3.4.2.7
The table shows appropriate indicators used to identify the equivalence point in titrations. For
NaOH and HCl the appropriate indicator is bromothymol blue.
A second titration was conducted by adding NaOH to a different acid. The pH in the flask
was recorded during the titration and Curve B was produced.
2007
9.3.4.2.7
What is the appropriate indicator for Curve B using the table?
(A) Methyl orange
(B) Methyl red
(C) Cresolphthalein
(D) Alizarin yellow
7 Which graph represents the enthalpy change for an acid-base neutralisation reaction?
2011
Question 29 (4 marks)
9.3.4.2.2
(a) Justify the continued use of the Arrhenius definition of acids and bases, despite the
development of the more sophisticated Brönsted–Lowry definition. (3 marks)
9.3.4.2.7
(b) Why does the neutralisation of any strong acid in an aqueous solution by any strong base
always result in a heat of reaction of approximately –57 kJ mol-1? (1 mark)
2005
9 Which of the following pairs would form a buffer solution?
9.3.4.2.9
2008
Question 26 (4 marks)
9.3.4.2.9
Explain how a buffer works with reference to a specific example in a natural system.
2011
Question 25 (3 marks)
9.3.4.2.9
Explain the role of the conjugate acid/base pair, H2PO4- / HPO42-, in maintaining the 3 pH of
living cells. Include chemical equations in your answer.
2005
Question 21 (5 marks)
9.3.4.3.1
Analyse how knowledge of the composition and properties of acids has led to changes in the
definition of acids.
2006
11 In 1884, Svante Arrhenius proposed a definition for acids. His definition was soon accepted
as superior to that put forward by earlier chemists.
9.3.4.3.1
Why was Arrhenius’ definition seen as a major improvement?
2006
(A) It explained why some acids do not contain oxygen.
(B) It showed how the solvent can affect the strength of an acid.
(C) It showed the relationship between pH and the concentration of H+ ions.
(D) It could be used to explain why some acids are strong and others are weak.
Question 21 (3 marks)
You performed a first-hand investigation to identify the pH of a range of salt solutions.
9.3.4.3.2
(a) Identify an acidic salt you used. (1 mark)
9.3.4.3.2
(b) Explain the acidic nature of the salt you selected. Include a balanced chemical equation in
your answer. (2 marks)
2011
16 Which statement correctly describes the pH at each titration equivalence point?
9.3.4.3.2
(A) The pH of both solutions will be the same.
(B) One of the solutions will be neutral while the other will have a pH higher than 7.
(C) One of the solutions will be neutral while the other will have a pH lower than 7.
(D) One of the solutions will have a pH higher than 7 while the other will have a pH lower than
7.
Question 16 (5 marks)
(a) Outline the procedure you would use to prepare a standard solution of sodium hydrogen
carbonate from solid sodium hydrogen carbonate. (3 marks)
2004
9.3.4.3.3
9.3.4.3.3
(b) Calculate the mass of solid sodium hydrogen carbonate required to make 250 mL of 0.12
mol L-1 solution. (2 marks)
2005
Question 24 (5 marks)
An antacid tablet is known to contain calcium carbonate (CaCO3). To determine the mass of
calcium carbonate in the tablet, the following procedure was used.
• The tablet was crushed and then placed in a beaker.
• A pipette was used to add 25.0 mL of 0.600 mol L–1 hydrochloric acid to the crushed tablet in
the beaker.
• Once the reaction between the calcium carbonate and hydrochloric acid had stopped,
phenolphthalein indicator was added to the reaction mixture.
• A teflon-coated burette was then used to add 0.100 mol L–1 sodium hydroxide to the beaker
to neutralise the excess hydrochloric acid.
• The phenolphthalein changed from colourless to pink after 14.2 mL of the sodium hydroxide
solution had been added.
9.3.4.3.3
(b) How many moles of hydrochloric acid were added to the tablet? (1 mark)
9.3.4.3.3
(c) Calculate the mass of calcium carbonate in the original antacid tablet. (3 marks)
2006
9 Which statement best describes the equivalence point in a titration between a strong acid and
a strong base?
9.3.4.3.3
2007
(A) The point at which the first sign of a colour change occurs
(B) The point at which equal moles of acid and base have been added together
(C) The point at which equal moles of H+ ions and OH– ions have been added together
(D) The point at which the rate of the forward reaction equals the rate of the reverse reaction
Question 21 (5 marks)
9.3.4.3.1
(c) 10 mL of 0.005 mol L–1 H2SO4 was diluted to 100 mL. What volume of 0.005 mol L–1
KOH is required to neutralise 15 mL of the diluted H2SO4 solution? (3 marks)
2008
Question 28 (6 marks) A standard solution was prepared by dissolving 1.314 g of sodium
carbonate in water. The solution was made up to a final volume of 250.0 mL.
9.3.4.3.3
(a) Calculate the concentration of the sodium carbonate solution. (2 marks)
This solution was used to determine the concentration of a solution of hydrochloric acid. Four
25.00 mL samples of the acid were titrated with the sodium carbonate solution. The average
titration volume required to reach the end point was 23.45 mL.
9.3.4.3.3
(b) Write a balanced equation for the titration reaction. (1 mark)
9.3.4.3.3
(c) Calculate the concentration of the hydrochloric acid solution. (3 marks)
2009
14 Citric acid, the predominant acid in lemon juice, is a triprotic acid. A student titrated 25.0
mL samples of lemon juice with 0.550 mol L–1 NaOH. The mean titration volume was 29.50
mL. The molar mass of citric acid is 192.12 g mol–1.
9.3.4.3.3
2011
9.3.4.3.3
What was the concentration of citric acid in the lemon juice?
(A) 1.04 g L–1
(B) 41.6 g L–1
(C) 125gL–1
(D) 374gL–1
18 A household cleaning agent contains a weak base with the formula NaX. 1.00 g of this
compound was dissolved in water to give 100.0 mL of solution. A 20.0 mL sample of the
solution was titrated with 0.100 mol L–1 hydrochloric acid, and required 24.4 mL of the acid
for neutralisation.
What is the molar mass of the weak base?
(A) 82.0 g
(B) 84.0 g
(C) 122 g
(D) 410 g
2009
Question 21 (6 marks)
The graph shows changes in pH for the titrations of equal volumes of solutions of two
monoprotic acids, Acid 1 and Acid 2.
(a) Explain the differences between Acid 1 and Acid 2 in terms of their relative strengths and
concentrations. (3 marks)
9.3.4.3.3
(b) Name the salt produced by the reaction of an acid of the same type as Acid 2 with
KOH(aq). (1 mark)
9.3.4.3.3
2009
Question 22 (7 marks)
The nitrogen content of bread was determined using the following procedure:
● A sample of bread weighing 2.80 g was analysed.
● The nitrogen in the sample was converted into ammonia.
−1
● The ammonia was collected in 50.0 mL of 0.125 mol L hydrochloric acid. All of the
ammonia was neutralised, leaving an excess of hydrochloric acid.
−1
● The excess hydrochloric acid was titrated with 23.30 mL of 0.116 mol L sodium hydroxide
solution.
9.3.4.3.3
(a) Write balanced equations for the TWO reactions involving hydrochloric acid. (2 marks)
9.3.4.3.3
(b) Calculate the moles of excess hydrochloric acid. (1 mark)
9.3.4.3.3
(c) Calculate the moles of ammonia. (2 marks)
2011
15 Which statement about the volume of base required to reach the equivalence point is
correct?
9.3.4.3.3
(A) The weak acid will require the same volume of base as the strong acid.
(B) The weak acid will require a larger volume of base than the strong acid.
(C) The weak acid will require a smaller volume of base than the strong acid.
(D) The volume of base required will depend on the molar mass of the acid used.
2010
Question 28 (8 marks)
9.3.4.3.3
The flowchart shown outlines the sequence of steps used to determine the concentration of an
unknown hydrochloric acid solution.
Describe steps A, B and C including correct techniques, equipment and appropriate
calculations. Determine the concentration of the hydrochloric acid.
2011
Question 26 (6 marks)
A manufacturer makes lemon cordial by mixing flavouring, sugar syrup and citric acid. The
concentration of the citric acid is determined by titration with NaOH.
The sodium hydroxide solution is prepared by dissolving 4.000 g of NaOH pellets in water to
give 1.000 L of solution. This solution is standardised by titrating 25.00 mL with a 0.1011 mol
–1
L standardised solution of HCl. The average titration volume is found to be 24.10 mL.
To analyse the lemon cordial 50.00 mL of the cordial is diluted to 500.0 mL. Then 25.00 mL
of the diluted solution is titrated with the NaOH solution to the phenolphthalein endpoint.
The following data were collected during one of the analysis runs of the lemon cordial.
9.3.4.3.3
(a) Why is the calculated concentration of the standardised NaOH solution different from the
concentration calculated using the mass given, assuming no human error occurred? (2 marks)
9.3.4.3.3
(b) Determine the concentration of citric acid in the lemon cordial. (4 marks)
2007
Question 25 (5 marks)
9.3.4.3.5
Sodium hydrogen carbonate, NaHCO3, is commonly used to neutralise chemical spills
that are a potential hazard to the environment.
Assess the effectiveness of NaHCO3 in this role, with reference to its chemical properties.
2002
6 Which is amphiprotic?
9.3.4
(A) H2SO4
(B) NH4+
(C) HCO3–
(D) SO42–
7 What did the Brönsted–Lowry definition of acids identify that made it a significant
improvement over earlier definitions?
2002
9.3.4
2003
9.3.4
(A) Acids contain hydrogen.
(B) Acids are proton donors.
(C) Acids contain oxygen.
(D) Acids are electron-pair acceptors.
14 In a titration of a strong base with a strong acid, the following procedure was used:
1. A burette was rinsed with water and then filled with the standard acid.
2. A pipette was rinsed with some base solution.
3. A conical flask was rinsed with some base solution.
4. A pipette was used to transfer a measured volume of base solution into the conical flask.
5. Indicator was added to the base sample and it was titrated to the endpoint with the acid.
Which statement is correct?
(A) The calculated base concentration will be correct.
(B) The calculated base concentration will be too low.
(C) The calculated base concentration will be too high.
(D) No definite conclusion can be reached about the base concentration.
2001
Question 21 (4 marks)
Barium hydroxide and sulfuric acid react according to the following equation:
Ba(OH)2 (aq) + H2SO4 (aq) → BaSO4 (s) + 2H2O(l)
9.3.4
(a) Name this type of chemical reaction. (1 mark)
9.3.4
(b) A 20 mL sample of barium hydroxide was titrated with 0.12 mol L–1 sulfuric acid. The
conductivity of the solution was measured throughout the titration and the results graphed, as
shown. (3 marks)
Explain the changes in conductivity shown by the graph.
2001
Question 23 (4 marks)
A household cleaning agent contains a weak base of general formula NaX. 1.00 g of this
compound was dissolved in 100.0 mL of water. A 20.0 mL sample of the solution was titrated
with 0.1000 mol L–1 hydrochloric acid and required 24.4 mL of the acid for neutralisation.
9.3.4
(a) What is the Brönsted–Lowry definition of a base? (1 mark)
9.3.4
(b) What is the molar mass of this base? (3 marks)
2003
Question 24 (4 marks)
9.3.4
Discuss factors that must be considered when using neutralisation reactions to safely
minimise damage in chemical spills.
2003
Question 23 (4 marks)
25.0 mL of 0.12 mol L-1 standard barium hydroxide solution was titrated with nitric acid. The
results are recorded in the table.
9.3.4
(b) Calculate the concentration of the nitric acid. (3 marks)
2002
8 In a titration, an acid of known concentration is placed in a burette and reacted with a base
that has been pipetted into a conical flask.
9.3.4
What should each piece of glassware be rinsed with immediately before the titration?
2003
15 Which of the following graphs shows how pH will vary when dilute HCl is added to 100
mL of dilute natural buffer solution with an initial pH of 7.0?
9.3.4
2006
7 Which class of compounds typically has a sweet smell?
9.3.5.2.1
(A) Esters
(B) Alkenes
(C) Haloalkanes
(D) Alkanoic acids
8 What is the systematic name of the molecule shown?
2011
9.3.5.2.2
2008
(A) Butyl butanoate
(B) Propyl butanoate
(C) Butyl propanoate
(D) Propyl propanoate
11 In which of the following alternatives are the three compounds listed in order of increasing
boiling point?
9.3.5.2.3
2011
9.3.5.2.3
(A) Pentane, butan-1-ol, propanoic acid
(B) Propanoic acid, butan-1-ol, pentane
(C) Propanoic acid, pentane, butan-1-ol
(D) Butan-1-ol, propanoic acid, pentane
6 Which property would be most useful in distinguishing between butan-1- ol and propan-1-ol?
(A) Boiling point
(B) Colour
(C) Conductivity
(D) Density
2004
1 Ethanol can be reacted with ethanoic acid to produce ethyl ethanoate. What type of reaction
is this?
9.3.5.2.4
2007
(A) Esterification
(B) Hydration
(C) Polymerisation
(D) Reduction
Question 23 (3 marks)
9.3.5.2.4
When hexanoic acid and ethanol are mixed together under certain conditions, esterification
occurs. Describe the conditions necessary for this reaction and give the structural formulae and
names of the products.
2009
10 Which of the following is the main organic product resulting from the reaction of butanoic
acid and pentanol?
9.3.5.2.4
2005
Question 20 (7 marks)
The flow chart shows a series of steps involved in the production of ethyl butanoate.
9.3.5.3.1
Describe the chemistry and procedure involved in each of these steps, using diagrams
where appropriate.
2009
9.3.5.3.1
Question 16 (3 marks)
Describe how to prepare an ester in the school laboratory. Include a specific safety precaution
in your answer.
2005
6 Which of the following is a common use for ethyl pentanoate?
9.3.5.3.2
(A) Flavouring
(B) Fuel
(C) Indicator
(D) Solvent
5 Why is ethanol used in preference to water as the main ingredient of perfume?
2008
9.3.5.3.2
2010
(A) Ethanol is cheaper to produce.
(B) Ethanol has no detectable odour.
(C) Ethanol dissolves esters more readily.
(D) Ethanol has a significantly lower density.
Question 22 (6 marks)
A student prepared the compound methyl propanoate in a school laboratory.
9.3.5.3.2
(a) Give a common use for the class of compounds to which methyl propanoate belongs. (1
mark)
9.3.5.3.1
(b) In the preparation of this compound a few drops of concentrated sulfuric acid were added to
the starting materials. The mixture was then refluxed for a period of time.
Why was it necessary to reflux the mixture? (2 marks)
9.3.5.2.2
(c) Name the TWO reactants used in preparing the methyl propanoate and draw their
structural formulae. (3 marks)
2001
Question 22 (6 marks)
9.3.5
Justify the procedure you used to prepare an ester in a school laboratory. Include relevant
chemical equations in your answer.
2002
9.3.5
9 The following list of steps refers to an experimental plan for making an ester in a flask. Some
of the steps in the list may NOT be required for this experiment. The steps are NOT in the
correct sequence.
1. Heat the mixture under reflux.
2. Add three drops of concentrated sulfuric acid.
3. Add 1 mL of ethanol.
4. Add 1 mL of ethene.
5. Add 1 mL of ethanoic acid.
6. Distil the mixture.
7. Add three drops of phenolphthalein indicator.
Which alternative is the best sequence for making an ester?
2003
(A) 3, 5, 7, 1
(B) 4, 3, 7, 6
(C) 5, 4, 2, 6
(D) 5, 3, 2, 1
Question 25 (4 marks)
9.3.5
Explain the trends in boiling points shown in the graph.
2002
10 Which equation represents esterification?
9.3.5
2003
Question 21 (5 marks)
You performed a first-hand investigation to prepare an ester by reflux.
9.3.5
(a) Identify the products formed when propanoic acid and butanol are refluxed with acid
catalyst. (1 mark)
9.3.5
(b) Draw a fully labelled diagram of the equipment assembled for use. (2 marks)
(c) Outline the advantages of using reflux to prepare the ester. (2 marks)
9.3.5