5070_w21_qp_21
A paper of Chemistry, 5070
Questions:
10
Year:
2021
Paper:
2
Variant:
1
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1
Choose from the following oxides to answer the questions. aluminium oxide calcium oxide iron(oxide magnesium oxide silicon dioxide sodium oxide sulfur dioxide Each oxide may be used once, more than once or not at all. State which oxide: has a simple molecular structure is a coloured solid contains ions with a 3+ charge is a product of the thermal decomposition of calcium carbonate contributes to acid rain.
7. Acids, bases and salts  →  7.2. Oxides
9. Metals  →  9.4. Reactivity series
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2
Dry air contains nitrogen, oxygen, noble gases and carbon dioxide. State the percentage of oxygen present in dry air. Carbon dioxide is removed from a sample of air by passing the air through aqueous sodium hydroxide. Explain why aqueous sodium hydroxide removes carbon dioxide from air. Describe how oxygen, nitrogen and the noble gases are separated from each other after carbon dioxide has been removed. Describe the test for oxygen. test observation Ozone, O3, is formed in the atmosphere by the reaction of nitrogen dioxide with oxygen in the presence of ultraviolet light. State the type of chemical reaction that takes place when ozone is formed in this way. Nitrogen dioxide is formed in internal combustion engines. State one other source of nitrogen dioxide in the atmosphere. A layer of ozone is present high in the atmosphere. State one problem for humans that can arise if the ozone layer is depleted by CFCs.
10. Chemistry of the environment  →  10.3. Air quality and climate
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3
Iron powder reacts with dilute sulfuric acid. Fe+ H2SO4FeSO4+ H2The graph shows the volume of hydrogen gas produced at 20 °C as the reaction proceeds. volume of hydrogen gas / cm3 time / min State how long it takes from the start of the experiment to collect 18 cm3 of hydrogen gas. The experiment is repeated at 30 °C. All other conditions are the same. Draw a line on the grid to show how the volume of hydrogen gas produced changes with time when the reaction is done at 30 °C. Describe and explain, using ideas about collisions between particles, how the rate of the reaction changes when the temperature of the reaction mixture is increased. All other conditions are the same. Describe and explain, using ideas about collisions between particles, how the rate of the reaction changes when larger pieces of iron are used. All other conditions are the same. Calculate the maximum volume, in dm3, of hydrogen formed when 3.36 g of iron react with excess dilute sulfuric acid at room temperature and pressure. Give your answer to three significant figures. maximum volume = dm3 Concentrated sulfuric acid is an oxidising agent. Describe a test for oxidising agents. test observations
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
6. Chemical reactions  →  6.2. Rate of reaction
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4
Alkenes are a homologous series of hydrocarbons. Alkenes are produced by cracking. State the meaning of the term cracking. Margarine is manufactured from vegetable oils using a nickel catalyst. Name the other reactant used in this reaction. State the type of chemical reaction which occurs when margarine is manufactured from vegetable oils. Ethanol is produced by the reaction of ethene with steam. Construct the equation for this reaction. An organic compound contains 54.5% carbon, 9.10% hydrogen and 36.4% oxygen by mass. Calculate the empirical formula of this compound. empirical formula
11. Organic chemistry  →  11.5. Alkenes
11. Organic chemistry  →  11.6. Alcohols
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5
Magnesium undergoes oxidation when it reacts with aqueous silver nitrate. Mg + 2Ag+ Mg2+ + 2Ag Explain how this equation shows that magnesium is oxidised. The reaction of magnesium with silver nitrate is exothermic. Complete the energy profile diagram for this reaction. Label reactants, products and ∆H. progress of reaction energy Acidified aqueous silver nitrate is added to a solution containing halide ions. A yellow precipitate is observed. State the name of the halide ion present in the solution. Silver is a metal. Use your knowledge of the structure of metals to explain why silver is malleable. The table gives information about the thermal decomposition of some metal carbonates. metal carbonate ease of thermal decomposition calcium carbonate decomposes at 900 °C magnesium carbonate decomposes at 540 °C sodium carbonate does not decompose below 1000 °C Describe how the ease of thermal decomposition depends on the position of these metals in the reactivity series.
9. Metals  →  9.4. Reactivity series
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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6
Chlorine reacts with phosphorus to form phosphorus(chloride. 3Cl2 + 2P 2PCl3 The reaction is exothermic. Explain in terms of bond breaking and bond forming why the reaction is exothermic. When chlorine reacts with aqueous potassium iodide a brown solution is formed. Name the products of this reaction. and When aqueous bromine is added to potassium chloride there is no reaction. Explain why there is no reaction. Phosphorus(chloride reacts with water to form a mixture of phosphorous acid, H3PO3, and hydrochloric acid. Construct the equation for this reaction.
5. Chemical energetics  →  5.1. Exothermic and endothermic reactions
11. Organic chemistry  →  11.4. Alkanes
9. Metals  →  9.4. Reactivity series
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7
This question is about metals and metal compounds. Silver is a transition element. Potassium is a metal in Group I of the Periodic Table. State two differences in the physical properties of silver and potassium. An ion of silver has the symbol 47 Ag+ Deduce the number of protons, neutrons and electrons in this ion. number of protons number of neutrons number of electrons Potassium reacts with water to form a gas which ‘pops’ with a lighted splint. Complete the equation for this reaction. K + H2O 2KOH + When zinc carbonate is warmed in a closed container, an equilibrium mixture is formed. ZnCO3ZnO+ CO2The forward reaction is endothermic. Describe and explain the effect, if any, on the position of equilibrium when the temperature is decreased. Describe and explain the effect, if any, on the position of equilibrium when the concentration of carbon dioxide is increased.
9. Metals  →  9.4. Reactivity series
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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8
The structure of angelic acid is shown. H CH3 H3C C C OH C O Explain how this structure shows that angelic acid is an unsaturated compound. Deduce the molecular formula of angelic acid. Angelic acid is a weak acid. Define the term acid. Explain the meaning of the term weak as applied to acids. Angelic acid can be polymerised. State the name of the type of polymerisation that occurs. Draw the partial structure of the polymer of angelic acid. Show two repeat units. Angelic acid reacts with methanol, CH3OH, to form an ester. Complete the structure of this ester to show all the atoms and all the bonds. H C C C H H H H C H H Construct the equation for the complete combustion of methanol.
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
11. Organic chemistry  →  11.7. Carboxylic acids
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9
This question is about ammonia and nitrates. State the source of the hydrogen and nitrogen used in the manufacture of ammonia by the Haber process. source of hydrogen source of nitrogen Ammonia is formed when aqueous ammonium sulfate is heated with sodium hydroxide. (NH4)2SO4 + 2NaOH 2NH3 + Na2SO4 + 2H2O A student adds 4.50 g of sodium hydroxide to 50.0 cm3 of 1.25 mol / dm3 aqueous ammonium sulfate. Show by calculation that the ammonium sulfate is in excess. When dilute sodium hydroxide is electrolysed, the hydroxide ions are converted to oxygen and water at the anode. Construct the ionic equation for the reaction taking place at the anode. The first stage in the test for nitrate ions is to heat aluminium and sodium hydroxide with a solution containing nitrate ions. State the type of chemical reaction which occurs when a solution containing nitrate ions is heated with aluminium and sodium hydroxide. Nitrates from fertilisers cause eutrophication when they are leached from soils into rivers. Describe the process of eutrophication.
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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10
This question is about elements in Group IV of the Periodic Table. The table shows some properties of the Group IV elements. element density at room temperature in g / cm3 melting point in °C boiling point in °C carbon 3550 silicon 2.34 germanium 5.35 tin lead 11.34 Predict the density of tin. Describe the general trend in the boiling points of the Group IV elements. Predict the state of silicon at 1600 °C. Give a reason for your answer. The structure of two compounds of silicon, P and Q, are shown. oxygen atom silicon atom chlorine atom P Q Explain in terms of structure and bonding why compound P has a high melting point and compound Q has a low melting point. compound P compound Q Draw a dot-and-cross diagram for a molecule of compound Q. Show only the outer shell electrons. A compound of carbon, hydrogen and silicon has the formula Si(CH3)4. Calculate the percentage by mass of carbon in this compound.
2. Atoms, elements and compounds  →  2.6. Giant covalent structures
8. The Periodic Table  →  8.1. Arrangement of elements
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