2019 - Q2
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Which of the following is an Arrhenius base?
A. Na
B. NaOH
C. Na2CO3
D. NaHCO3
2019 - Q5
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The diagram represents the titration curve for a reaction between a particular acid an particular base.
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Which indicator would be best for this titration?
2020 - Q25 (7 marks)
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Citric acid reacts with sodium hydroxide according to the following chemical equation:
C6H8O7(aq) + 3NaOH(aq) --> Na3C6H5O7(aq) + 3H2O(l) .
Various volumes of 1.0 mol L−1 citric acid solution were mixed with 8.0 mL of a sodium hydroxide solution of unknown concentration and sufficient deionised water added to make the total volume of the resulting solution 14.0 mL. The change in temperature of each solution was measured.
The data are given in the table.
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By graphing the data in the table and performing relevant calculations, determine the concentration of the sodium hydroxide solution.
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2020 - Q2
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Which indicator in the table would be best for distinguishing between a face cleanser (pH =5.0) and a soap (pH = 9.0)?
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2020 - Q10
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Equimolar solutions of NaCl(aq), NH4Cl(aq) and NaCH3COO(aq) were prepared.
In which of the following are these salt solutions listed from least to most acidic?
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2020 - Q34 (4 marks)
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The effect of concentration on the pH of acrylic acid (C2H3COOH) and hydrochloric acid (HCl) solutions is shown in the graph. Both of these acids are monoprotic.
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Explain the trends in the graph. Include relevant chemical equations in your answer.
2020 - Q36 (5 marks)
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100.00 mL of 2.00 mol L−1 HCl(aq) was initially at a temperature of 22.5°C. The mass of this solution was 103 g.
10.0 g of solid NaOH was added to the acid. The specific heat capacity of the resulting solution was 3.99 J g−1 K−1.
Assuming no energy loss to the environment, calculate the maximum temperature reached by the solution.
Use the following information in your calculations.
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2021 - Q32 (4 marks)
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The molar enthalpies of neutralisation of three reactions are given.
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Reaction 1:
HCl(aq) + KOH(aq) + KCl(aq) --> H2O(l) DH = –57.6 kJ mol−1
Reaction 2:
HNO3(aq) + KOH(aq) --> KNO3(aq) + H2O(l) DH = –57.6 kJ mol−1
Reaction 3:
HCN(aq) + KOH(aq) --> KCN(aq) + H2O(l) DH = –12.0 kJ mol−1
Explain why the first two reactions have the same enthalpy value but the third reaction has a different value.
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2022 - Q26 (4 marks)
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Students conducted an experiment to determine deltaH for the reaction between sodium hydroxide and hydrochloric acid.
The data from one student are shown in the table below.
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Assume that all the solutions have the same specific heat capacity of water.
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(a) Calculate the heat energy released in this experiment. (2 marks)
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(b) A second student using the same procedure obtained 2.6 × 10^3 J for the heat energy released in their experiment. Use this value to determine the enthalpy of neutralisation, delta H , in kJ mol−1, for the reaction shown.
(2 marks)
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NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l)
