Question
The structures of six compounds are shown below.
Answer the following questions about these substances.
Each compound may be used once, more than once or not at all.
(a) Which substance, A, B, C, D, E or F,
(i) gives a white precipitate on addition of an aqueous solution of sodium sulfate,
(ii) is a component of many fertilisers,
(iii) contains a Group III element,
(iv) is an acidic gas at room temperature,
(v) turns anhydrous cobalt chloride pink,
(vi) is the main component of natural gas?
(b) Compound A can be made by direct combination of chlorine and aluminium using the apparatus shown below.
(i) On the diagram above, draw an arrow to show where heat is applied.
(ii) Suggest one safety precaution that should be taken when carrying out this experiment.
(iii) Complete the symbol equation for this reaction.
\(2Al + ……..Cl_2 → Al_2Cl_6\)
Answer/Explanation
Answer:
(a) (i) F/ barium chloride/\(BaCl_2\);
(ii) D/ ammonium sulfate/\((NH_4)_2SO_4\);
(iii) A/Al /Al2Cl6 / aluminium chloride;
(iv) E/HCl/ hydrogen chloride;
(v) B/water/\(H_2O\);
(b) (i) arrow under the aluminium foil;
(ii) fume cupboard;
(iii) \(3(Cl_2)\);
Question
A student used chromatography to separate the dyes in the blue ink from a ball-point pen. She used the equipment shown in the diagrams below.
(a) Complete the diagram below to show how she set up the apparatus.[3]
(b) Describe how chromatography could be used by the student to separate the dyes.[3]
(c) The student used water as a solvent. Suggest a different solvent that she could use.[1]
(d) The diagram below shows the results of the chromatography using the blue ink, B, and several pure dyes, W, X, Y and Z.
(i) Which of the dyes, W, X, Y and Z, were in the blue ink?[1]
(ii) How many dyes in the ink had been separated by this chromatography?[1]
(e) The diagram shows the ball-point pen used in the experiment.
(i) The cap of the pen is made of poly(ethene).
Describe the formation of poly(ethene) from ethene. In your answer, include the words:[2]
-
-
- monomer,
- polymer.
-
(ii) The tip of the pen is made from an alloy.
What is meant by the term alloy ?[1]
(f) The table shows some properties of four alloys.
(i) How does the strength of the steel and aluminum alloys vary with their thermal conductivity?[1]
(ii) Which one of these alloys is the best one to use to make the body of an aircraft? Give two reasons for your answer.[3] [Total: 16]
Answer/Explanation
Ans:
7 (a) square / rectangular sheet of paper in chromatography tank;
note: the sheet should not touch the sides of the beaker
solvent at bottom of tank with paper dipping into it;
note: solvent does not have to be labelled / paper can just touch the surface
But there should be no gap between the solvent and the paper
watch glass over the tank (this can just be shown as a line);
(b) place spot of ink / dye on the paper;
note: answer must imply a spot or drop (not just ink put on paper)
above the solvent level;
let the solvent run up the paper / solvent moves the dyes up the paper / some idea that solvent is needed for the movement of the spots;
(c) any suitable solvent e.g. ethanol / butanol / ester / alcohol
(d) (i) W, X and Y;
(ii) 4 / four;
(e) (i) idea that ethene is the monomer / idea that monomers are the simple (or basic) units which add together;
idea that poly(ethene) is the polymer / idea that the polymer is formed by adding ethene units / simple units combine to form polymer / idea that polymer is a very long (hydrocarbon) chain;
note: (ethene) monomers join to make a polymer = 2 marks
(ii) mixture of metals / mixture of metal + non metal;
(f) (i) increasing strength decreases (thermal) conductivity / the lower the conductivity the higher the strength;
(ii) high strength aluminum;
has high strength / it is strong / aircraft body need to be strong;
it has low density / it is light(weight) / aircraft body needs to be light(weight)