0620_s14_qp_31
A paper of Chemistry, 0620
Questions:
8
Year:
2014
Paper:
3
Variant:
1
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1
The table below gives the composition of six particles which are either atoms or ions. particle number of protons number of neutrons number of electrons A B C D E F Which particles are atoms? Explain your choice. Which particle is a negative ion and why has this particle got a negative charge? Which particles are positive ions? Explain why particle A and particle D are isotopes.
2. Atoms, elements and compounds  →  2.2. Atomic structure and the Periodic Table
2. Atoms, elements and compounds  →  2.4. Ions and ionic bonds
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3
Different gases diffuse at different speeds. What is meant by the term diffusion? What property of a gas molecule affects the speed at which it diffuses? Helium is a gas used to fi ll balloons. It is present in the air in very small quantities. Diffusion can be used to separate it from the air. Air at 1000 °C is on one side of a porous barrier. The air which passes through the barrier has a larger amount of helium in it. Why does the air on the other side of the barrier contain more helium? Why is it an advantage to have the air at a high temperature? Most helium is obtained from natural gas found in the USA. Natural gas contains methane and 7% helium. One possible way to obtain the helium would be to burn the methane. Write an equation for the complete combustion of methane. Suggest why this would not be a suitable method to obtain the helium. Suggest another method, other than diffusion, by which helium could be separated from the mixture of gases in natural gas.
1. States of matter  →  1.2. Diffusion
1. States of matter  →  1.1. Solids, liquids and gases
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4
In the Periodic Table, the elements are arranged in columns called Groups and in rows called Periods. Complete the table for some of the elements in Period 3. group number I II III IV V VI VII symbol Na Mg Al Si P S Cl number of valency electrons valency What is the relationship between the group number and the number of valency electrons? Explain the relationship between the number of valency electrons and the valency for the elements Na to Al, for the elements P to Cl. Across a period, the elements change from metallic to non-metallic. Describe how the type of oxide changes across this period. Describe how the type of bonding in the chlorides formed by these elements changes across this period.
8. The Periodic Table  →  8.1. Arrangement of elements
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6
Hydrogen peroxide decomposes to form water and oxygen. This reaction is catalysed by manganese(oxide. 2H2O2→ 2H2O+ O2The rate of this reaction can be investigated using the following apparatus. aqueous hydrogen peroxide and manganese(oxide oxygen gas 40 cm3 of aqueous hydrogen peroxide was put in the fl ask and 0.1 g of small lumps of manganese(oxide was added. The volume of oxygen collected was measured every 30 seconds. The results were plotted to give the graph shown below. volume of oxygen time t1 t2 t3 How do the rates at times t1, t2 and t3 differ? Explain the trend in reaction rate that you described in . The experiment was repeated using 0.1 g of fi nely powdered manganese(oxide. All the other variables were kept the same. On the axes opposite, sketch the graph that would be expected. Explain the shape of this graph. Describe how you could show that the catalyst, manganese(oxide, was not used up in the reaction. Manganese(oxide is insoluble in water. In the fi rst experiment, the maximum volume of oxygen produced was 96 cm3 measured at r.t.p. Calculate the concentration of the aqueous hydrogen peroxide in mol / dm3. 2H2O2→ 2H2O+ O2number of moles of O2 formed = number of moles of H2O2 in 40 cm3 of solution = concentration of the aqueous hydrogen peroxide in mol / dm3 =
6. Chemical reactions  →  6.2. Rate of reaction
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7
One way of establishing a reactivity series is by displacement reactions. A series of experiments was carried out using the metals lead, magnesium, zinc and silver. Each metal was added in turn to aqueous solutions of the metal nitrates. The order of reactivity was found to be: magnesium most reactive zinc ↓ lead silver least reactive Complete the table. = reacts = does not react metal aqueous solution lead Pb magnesium Mg zinc Zn silver Ag lead(nitrate    magnesium nitrate zinc nitrate silver nitrate Displacement reactions are redox reactions. On the following equation, draw a ring around the reducing agent and an arrow to show the change which is oxidation. Zn + Pb2+ → Zn2+ + Pb Complete the following ionic equation. Zn + 2Ag+ → + Another way of determining the order of reactivity of metals is by measuring the voltage and polarity of simple cells. The polarity of a cell is shown by which metal is the positive electrode and which metal is the negative electrode. An example of a simple cell is shown below. zinc electrode lead electrode electrolyte of dilute acid voltmeter + – V Mark on the above diagram the direction of the electron fl ow. Explain, in terms of electron transfer, why the more reactive metal is always the negative electrode. The following table gives the polarity of cells using the metals zinc, lead, copper and manganese. cell electrode 1 polarity electrode 2 polarity A zinc – lead + B manganese – lead + C copper + lead – What information about the order of reactivity of these four metals can be deduced from the table? What additional information is needed to establish the order of reactivity of these four metals using cells?
9. Metals  →  9.4. Reactivity series
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8
Polymers are made by the polymerisation of simple molecules called monomers. The structural formula of a polymer is given below. n CH CH3 CH CH3 This polymer is made by addition polymerisation. Draw the structural formula of its monomer. The two monomers shown below form a nylon which is a condensation polymer. NH2 H2N COOH HOOC Draw its structural formula showing one repeat unit of the polymer. Name the natural macromolecule which contains the same linkage as nylon. Explain the difference between addition polymerisation and condensation polymerisation. Many polymers are non-biodegradable. Explain the term non-biodegradable. State three problems caused by the disposal of non-biodegradable polymers. Storage tanks for cold water are now made from polymers because they are cheaper than metal tanks. Suggest two other advantages of making cold water tanks from polymers.
11. Organic chemistry  →  11.8. Polymers
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