0620_s18_qp_42
A paper of Chemistry, 0620
Questions:
7
Year:
2018
Paper:
4
Variant:
2
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This question is about the elements in Period3 of the Periodic Table. Na Mg Al Si P S Cl Ar For each of the following, identify a Period3 element which matches the description. Each element may be used once, more than once or not at all. State which Period3 element: forms an oxide with a macromolecular structure is extracted from the ore bauxite is soft, metallic and stored in oil is a green gas at room temperature and pressure provides an inert atmosphere in lamps forms two different oxides during the Contact process is non‑metallic and an important component of fertilisers.
8. The Periodic Table  →  8.1. Arrangement of elements
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Potassium reacts with bromine at room temperature to form potassium bromide. Write a chemical equation for this reaction. Include state symbols. Potassiumbromide exists as an ioniclattice. Potassiumbromide does not conduct electricity when solid but does conduct electricity when molten. What is meant by the term ionic lattice? Explain why potassium bromide does not conduct electricity when solid but does conduct electricity when molten. Concentrated aqueous potassium bromide is an electrolyte. What is meant by the term electrolyte? Describe the electrolysis of concentrated aqueous potassium bromide. Include: ● ● an ionic half-equation for the reaction at the cathode ● ● the name of the product at the anode ● ● the name of the potassium compound formed. When molten potassium bromide is electrolysed, the product at the cathode is different. Name the product at the cathode when molten potassiumbromide is electrolysed. Iodine reacts with chlorine to form iodine monochloride, ICl, as the only product. Write a chemical equation for this reaction. Draw a dot-and-cross diagram to show the electron arrangement in a molecule of iodinemonochloride. Show outer shell electrons only. Potassiumbromide has a melting point of 734 °C. Iodinemonochloride has a melting point of 27 °C. In terms of attractive forces, explain why there is a large difference between these melting points. When chlorine gas is passed through aqueous potassium bromide, a redox reaction occurs. The ionic equation is shown. Cl 2 + 2Br – 2Cl – + Br2 Write an ionic half-equation showing what happens to the chlorine molecules, Cl 2, in this reaction. Explain why the bromide ions, Br –, act as reducing agents in this reaction.
4. Electrochemistry  →  4.1. Electrolysis
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Hydrogen and iodine react together in a reversible reaction. Hydrogen iodide is formed. H2+ I22HIcolourless purple colourless gas gas gas The forward reaction is exothermic. A gas syringe containing an equilibrium mixture of hydrogen, iodine and hydrogen iodide gases was sealed and heated to 250 °C. The equilibrium mixture was a pale purple colour. end blocked equilibrium mixture of hydrogen, iodine and hydrogen iodide What is meant by the term equilibrium? The plunger of the gas syringe was pressed in while the end of the gas syringe was blocked. This increased the pressure. The position of the equilibrium did not change. The colour of the gaseous mixture turned darker purple. Give a reason why the position of the equilibrium did not change. Suggest why the gaseous mixture turned darker purple, even though the position of the equilibrium did not change. The temperature of the gas syringe was increased to 300 °C. What happened to the position of the equilibrium when the temperature of the gas syringe was increased from 250 °C to 300 °C? What happened to the rate of the forward reaction and the rate of the backward reaction when the temperature of the gas syringe was increased from 250 °C to 300 °C? rate of the forward reaction rate of the backward reaction
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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All sodium salts are soluble in water. All nitrates are soluble in water. Barium carbonate is insoluble in water. Describe how you would make a pure, dry sample of barium carbonate by precipitation. Include: ● ● the names of the starting materials ● ● full practical details ● ● a chemical equation. Nitrates decompose when heated. Write a chemical equation for the decomposition of sodiumnitrate when it is heated. The unbalanced chemical equation for the decomposition of hydrated copper(nitrate crystals is shown. Balance the chemical equation for this reaction. 2Cu(NO3)2.3H2OCuO+ NO2+ O2+ H2O When the hydrated copper(nitrate crystals are heated, steam is produced. When the steam condenses on a cool surface, it turns into a colourless liquid. Anhydrous cobalt(chloride is used to show that the colourless liquid contains water. How does the colour of the anhydrous cobalt(chloride change? from to  How would the student test to determine if the water produced in is pure?
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
10. Chemistry of the environment  →  10.1. Water
7. Acids, bases and salts  →  7.3. Preparation of salts
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Many organic compounds, such as alcohols, carboxylicacids and esters, contain the elements carbon, hydrogen and oxygen only. CompoundR has the following composition by mass: C, 60.00%; H, 13.33%; O, 26.67%. Calculate the empirical formula of compound R.  empirical formula = CompoundS has the empirical formula C2H4O and a relative molecular mass of 88. Calculate the molecular formula of compound S. molecular formula = Compounds T and V both have the molecular formula C3H6O2. ● ● Compound T produces bubbles of carbon dioxide gas when it is added to aqueous sodiumcarbonate. ● ● Compound V is an ester. What is the name given to compounds with the same molecular formula but different structures? Draw the structures of compounds T and V. Show all of the atoms and all of the bonds. compound T compound V All compounds with the molecular formula C3H6O2 can undergo complete combustion in an excess of oxygen. Complete the chemical equation for this reaction. C3H6O2 + + Compound W has the molecular formula C2H6O. Compound W reacts when heated with ethanoicacid and a catalyst to produce a sweet‑smelling liquid. Give the name of the homologous series to which compound W belongs. Draw the structure of compoundW. Show all of the atoms and all of the bonds.  Alkanes and alkenes are hydrocarbons. What is meant by the term hydrocarbon? State the general formula of: alkanes alkenes Ethanol can be produced from long‑chain alkanes as shown. step 1 step 2 long‑chain alkane ethene ethanol Describe the two‑stage manufacture of ethanol from the long‑chain alkane octane, C8H18. Include: ● ● the names of the types of chemical reactions that occur ● ● reaction equations ● ● reaction conditions. step 1 step 2
11. Organic chemistry  →  11.2. Naming organic compounds
11. Organic chemistry  →  11.1. Formulae, functional groups and terminology
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