Question
(a) The apparatus used for distillation is shown.
(i) Complete the box to name the apparatus. [1]
(ii) Describe and explain how the water is separated from the aqueous copper(II) sulfate by distillation.
……………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………… [3]
(b) A sample of solid hydrated copper(II) sulfate is heated gently in a test-tube.
\(CuSO_4.5H_2O\rightleftharpoons CuSO_4 + 5H_2O\)
hydrated
copper(II) sulfate
Solid hydrated copper(II) sulfate is blue.
Describe two observations when the sample of solid hydrated copper(II) sulfate is heated gently in a test-tube.
1 ……………………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………………….[2]
(c) Copper(II) sulfate can be prepared by heating an excess of copper(II) oxide with dilute sulfuric acid.
(i) Complete the chemical equation for this reaction.
\(CuO + H_2SO_4 \rightarrow CuSO_4 + …………………\)[1]
(ii) What method is used to separate the excess copper(II) oxide from the solution?
……………………………………………………………………………………………………………………… [1]
(d) Copper(II) oxide can be reduced by hydrogen.
\(CuO + H_2 \rightarrow Cu + H_2O\)
How does this equation show that copper(II) oxide is reduced?
………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………. [1]
(e) The chemical equation for the reaction of copper with concentrated nitric acid is shown.
\(Cu + 4HNO_3 \rightarrow Cu(NO_3)_2 + 2NO_2 + 2H_2O\)
Complete the word equation for this reaction.
Answer/Explanation
(a)(i) (Liebig) condenser (1)
(a)(ii) One mark each for any three of:
• water has lower boiling point than copper(II) sulfate
• heat the aqueous copper(II) sulfate
• water turns to steam but copper(II) sulfate remains (in flask)
• steam turns to liquid in condenser
(b) colourless liquid collects / condenses at top of the tube (1)
copper(II) sulfate turns white (1)
(c)(i) \(H_2O\)
(c)(ii) filtration / filter
(d) oxygen removed from the copper oxide / copper oxide loses oxygen / it loses oxygen (1)
(e) (copper + nitric acid) → copper nitrate + nitrogen dioxide + water (2)
If 2 marks not scored:
1 mark for correct names of two products
Question
Rhenium is a metal.
(a) Describe three physical properties of rhenium.
…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….. ……………………………………………………………………………………………………………………………. [3]
(b) The structure of a rhenium chloride molecule is shown.
Determine the simplest formula for this chloride of rhenium.
……………………………………………………………………………………………………………………………. [1]
(c) Rhenium oxide is a yellow solid which undergoes sublimation at a low temperature. What is the meaning of the term sublimation?
……………………………………………………………………………………………………………………………. [1]
(d) Rhenium oxide reacts with water to form perrhenic acid. Perrhenic acid is strongly acidic.
(i) Which one of the following pH values represents an acidic solution? Draw a ring around the correct answer.
pH 2 pH 7 pH 9 pH 14
[1]
(ii) Perrhenic acid reacts with potassium hydroxide. Complete the word equation for this reaction.
(iii) Which one of the following compounds will react with perrhenic acid? Tick one box.
(e) Potassium perrhenate has a similar formula to potassium manganate(VII). Potassium manganate(VII) decomposes to give off oxygen. Describe a test for oxygen.
test ……………………………………………………………………………………………………………………………
result …………………………………………………………………………………………………………………………
[2]
[Total: 10]
Answer/Explanation
(a) any three from:
• silvery / shiny / lustrous
• conducts heat/ conducts electricity
• malleable
• ductile
• sonorous
• high melting point/ high boiling point
• strong/ hard
• high density
(b) \(ReCl_3\);
(c) change of state (directly) from solid to gas / gas to solid;
(d)(i) pH 2;
(d)(ii) water;
(d)(iii) potassium carbonate;
(e) glowing splint; relights / idea of bursting into flame;
Question
Calcium carbonate reacts with dilute hydrochloric acid.
\(CaCO_3(s) + 2HCl(aq) → CaCl_2(aq) + CO_2(g) + H_2O(I)\)
A student investigated this reaction by measuring the volume of carbon dioxide released every minute at constant temperature.
(a) Draw a diagram of the apparatus that the student could use to investigate this reaction.
(b)The graph shows the results of this reaction using three samples of calcium carbonate of the same mass: large pieces, medium-sized pieces and small pieces.
(i) Which sample, large, medium or small pieces, gave the fastest initial rate of reaction? Use the graph to explain your answer.
…………………………………………………………………………………………………………………………………………………………………………………………………………………………………. [2]
(ii) The experiment was repeated using powdered calcium carbonate of the same mass. Draw a line on the grid above to show how the volume of carbon dioxide changes with time for this experiment. [2]
(iii) At what time was the reaction just complete when small pieces of calcium carbonate were used?
……………………………………………………………………………………………………………….. [1]
(c) When calcium carbonate is heated strongly, calcium oxide is formed.
(i) Give one use of calcium oxide.
……………………………………………………………………………………………………………….. [1]
(ii)What type of oxide is calcium oxide?
Explain your answer.
…………………………………………………………………………………………………………………………………………………………………………………………………………………………………. [2]
[Total: 10]
Answer/Explanation
(a) (gas) syringe leading to flask / beaker/ test tube OR flask and tube leading to upturned measuring cylinder over trough of water; closed apparatus with no air gaps;
(b)(i)
small pieces;
line/ curve/ graph steepest;
(b)(ii)
line to the left of the small pieces starting at (0, 0); finishing at\( 45cm^3\) and before the other lines;
(b)(iii) any value between 205s and 215s (inclusive);
(c)(i) neutralising (acidic) soils / neutralising (acidic) waste/ steelmaking/ self-heating cans / making concrete/ making glass /water treatment/ making plaster/ making paper/ flue-gas desulfurisation/ neutralising acids / making limewater;
(c)(ii)
basic oxide;
because it is a metal oxide/ because it would react with acid/ neutralizes acids / calcium is on the left of the Periodic
Table;