9701_w16_qp_21
A paper of Chemistry, 9701
Questions:
5
Year:
2016
Paper:
2
Variant:
1
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1
A 0.17 g sample of a Group 14 chloride, XCl 4, reacted with water to produce an oxide, XO2, and HCl. equation 1 XCl 4+ 2H2O→ XO2+ 4HCl The HCl produced was absorbed in 100 cm3 of 0.10 mol dm–3 sodium hydroxide solution (an excess). In a titration, the unreacted sodium hydroxide solution required 30.0 cm3 of 0.20 mol dm–3 hydrochloric acid for complete neutralisation. Calculate the amount, in moles, of hydrochloric acid used in the titration to neutralise the unreacted sodium hydroxide solution. amount = mol Write the equation for the reaction between hydrochloric acid and sodium hydroxide. Calculate the amount, in moles, of sodium hydroxide neutralised in the titration. amount = mol Calculate the amount, in moles, of sodium hydroxide that reacted with the HCl produced by the reaction in equation 1. amount = mol Calculate the amount, in moles, of HCl produced by the reaction in equation 1. amount = mol Calculate the amount, in moles, of XCl 4 in the original 0.17 g sample. amount = mol Calculate the molecular mass, Mr, of XCl 4. Mr = Calculate the relative atomic mass, Ar, of X and suggest its identity. Ar of X = identity of X
11. Group 17  →  11.4. The reactions of chlorine
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
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2
For many compounds the enthalpy change of formation cannot be calculated directly. An indirect method based on enthalpy changes of combustion can be used. The enthalpy change of combustion can be found by a calorimetry experiment in which the heat energy given off during combustion is used to heat a known mass of water and the temperature change recorded. Explain the meaning of the term standard enthalpy change of combustion. Write the equation for the complete combustion of ethanol, C2H5OH. In an experiment to determine the enthalpy change of combustion of ethanol, 0.23 g of ethanol was burned and the heat given off raised the temperature of 100 g of water by 16.3 °C. Calculate the heat energy change, q, during the combustion of 0.23 g of ethanol. q = J Calculate the enthalpy change on burning 1 mole of ethanol. Include a sign in your answer. ∆H = kJ mol–1 Suggest two reasons why the value for the enthalpy change of combustion of ethanol determined by a simple laboratory calorimetry experiment is likely to be lower than the true value. The table gives some enthalpy change of combustion values. substance enthalpy change of combustion / kJ mol–1 C–393.5 H2–285.8 C3H7OH–2021.0 Construct a labelled energy cycle to show how these values could be used to calculate the enthalpy change of formation of C3H7OH, ∆Hf. 3C+ 4H2+ 1 2 O2∆Hf C3H7OH Calculate the enthalpy change of formation, ∆Hf, of C3H7OH. ∆Hf = kJ mol–1
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
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3
The elements in Group 2 and their compounds show various trends in their physical and chemical properties. The graph below shows the radius values of the atoms and 2+ ions of the elements in Group 2. 0.25 0.20 0.15 0.10 0.05 radius / nm Be Mg Ca Sr element Ba Ra Explain why both lines show a steady increase in the values of the radii down the group. State and explain which line represents the atomic radii and which represents the ionic radii. L is a salt of a Group 2 element M. When L is heated strongly a brown gas is observed and a white solid remains. The white solid dissolves in water to form a colourless solution of the metal hydroxide M(OH)2. Addition of dilute sulfuric acid to this colourless solution produces a dense white precipitate. Identify the anion in salt L. Identify the element M and write an ionic equation for the formation of the white precipitate with sulfuric acid. M = equation Give the formula of salt L and use it to write an equation for the thermal decomposition of salt L. formula of salt L equation Calcium carbonate and calcium hydroxide can both be used in agriculture to neutralise acidic soils. Write ionic equations for the neutralisation of acid by each of calcium hydroxide and calcium carbonate. calcium hydroxide calcium carbonate Suggest and explain why calcium carbonate is a better choice than calcium hydroxide for this purpose in areas of high rainfall. Magnesium reacts with both cold water and steam. Give the formula of the magnesium-containing product of each of these reactions. with cold water with steam
10. Group 2  →  10.1. Similarities and trends in the properties of the Group 2 metals, magnesium to barium, and their compounds
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
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4
In each section of this question an organic compound is shown. For each compound give its name and answer the questions about it. CH3CH2CH(CH3)CH=CHCH3 name This compound shows stereoisomerism. Define stereoisomerism. State and explain how many stereoisomers of this structure there are. (CH3)2C=C(CH3)2 name Draw the skeletal formula of the organic product of the reaction of this compound with cold, dilute, acidified manganate(ions. Name the organic product of the reaction of this compound with hot, concentrated, acidified manganate(ions. Draw the structure of part of a molecule of the addition polymer formed from this compound, showing exactly three repeat units. (CH3)2C=CH2 name Complete the mechanism for the reaction of this compound with hydrogen bromide. Include all necessary curly arrows, lone pairs, charges and partial charges. H3C CH2 CH3 C H3C CH3 CH3 C Br H Br Br – 2-bromomethylpropane Explain fully why 2-bromomethylpropane is the major product of this reaction while only relatively small amounts of 1-bromomethylpropane are produced.
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
14. Hydrocarbons  →  14.2. Alkenes
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