Question
(a) Magnesium is manufactured by the electrolysis of molten magnesium chloride.
(i) The negative electrode is made of iron.
Suggest a non-metal which could be used for the positive electrode.
Give a reason for your answer.[2]
(ii) Predict the products of the electrolysis of molten magnesium chloride at:[2]
the positive electrode
the negative electrode.
(b) The following statements are about the procedure for making crystals of hydrated magnesium chloride from magnesium and dilute hydrochloric acid.
-
- Leave the mixture until no more bubbles are seen.
- Leave the mixture at room temperature to form more crystals.
- Add an excess of magnesium to dilute hydrochloric acid.
- Warm the filtrate to the point of crystallization.
- Filter off the crystals and dry between filter papers.
- Filter off the excess magnesium.
Put the statements A, B, C, D, E and F in the correct order.
The first one has been done for you.
(c) Magnesium is a metal in Group II of the Periodic Table.
Copper is a transition element.
Copper has a higher melting point and a higher boiling point than magnesium.
Describe two other properties of copper which are different from those of magnesium.[2]
1
2
(d) Chromatography can be used to separate a mixture of ions from different transition element compounds.
Four samples, R, S, T and U, each containing transition element ions, were placed on a piece of chromatography paper.
Two solutions, Y and Z, each containing only one type of transition element ion were also placed on the same piece of chromatography paper.
The results of the chromatography are shown.
(i) Which sample, R, S, T or U, contains the same ions as both solution Y and solution Z?[1]
(ii) Which sample, R, S, T or U, does not contain the same ions as either solution Y or solution Z?[1]
(iii) In which sample, R, S, T or U, has the greatest number of transition element ions been separated?[1] [Total: 11]
Answer/Explanation
Ans:
(a)(i) graphite (1)
conducts electricity / inert (1)
(a)(ii) positive electrode: chlorine (1)
negative electrode: magnesium (1)
b) (C), A, F, D, B, E (2)
if 2 marks not scored 1 mark for 1 consecutive pair reversed
(c) 1 mark each for any two of:
-
- high density ORA for Mg
- forms coloured compounds ORA for Mg
- forms ions with different charges / has variable oxidation number ORA for Mg
- forms complex ions ORA for Mg
- copper is catalyst ORA for Mg
- reference to difference in chemical properties e.g. magnesium reacts with dilute acid / copper does not react with dilute acid
(d)(i) R
(d)(ii) T
(d)(iii) R
Question
Alcohols are a ‘family’ of organic molecules which have the same general formula.
(a) What is the name given to any ‘family’ of organic molecules which have the same general formula and similar chemical properties?[1]
(b) Give the general formula of alcohols.[1]
(c) Propan-1-ol can be made from propene.
(i) Name the reagent and give the conditions needed to convert propene into propan-1-ol.[2]
reagent
conditions
(ii) Write a chemical equation for the complete combustion of propan-1-ol.[2]
(d) A simple sugar can be represented as shown.
Simple sugars can be polymerised to make more complex carbohydrates.
(i) Complete the diagram to show part of a carbohydrate polymer made from the simple sugar shown.[2]
(ii) Name the chemical process which occurs when a carbohydrate polymer is broken down into simple sugars.[1]
(iii) What conditions are needed for this process to occur?[1]
(e) Chromatography can be used to identify simple sugars in a mixture.
A student analyzed a mixture of simple sugars by chromatography. All the simple sugars in the mixture were colourless.
(i) What is the name given to the type of substance used to identify the positions of the simple sugars on the chromatogram?[1]
(ii) The student calculated the Rf value of a spot on the chromatogram.
Complete the expression for the Rf value of the spot.
Rf = [1]
(iii) How could a student identify a simple sugar from its Rf value?[1]
(iv) Sometimes not all the substances in a mixture can be identified from the chromatogram produced.
Explain why this may happen.[1] [Total: 14]
Answer/Explanation
Ans:
5(a) homologous series
5(b) CnH2n+2O OR CnH2n+1OH
5(c)(i) M1 steam
M2 catalyst
5(c)(ii) 2C3H7OH + 9O2 → 6CO2 + 8H2O
M1 species
M2 fully correct equation
5(d)(i) M1 at least one –O– link between two blocks
M2 correct structure including continuation bonds
5(d)(ii) hydrolysis
5(d)(iii) enzyme OR heat + acid
5(e)(i) locating ((re)agent)
5(e)(ii) distance travelled by substance
distance travelled by solvent
5(e)(iii) compare to known data
5(e)(iv) similar Rf values
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)