9701_s20_qp_22
A paper of Chemistry, 9701
Questions:
5
Year:
2020
Paper:
2
Variant:
2
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1
Gallium is an element in Group13. A sample of gallium is analysed using a mass spectrometer. The mass spectrum produced is shown. % relative abundance mass 69 71 60.11% 39.89% Explain what is meant by the term relative atomic mass. Calculate the relative atomic mass of gallium in this sample. Give your answer to 4 significant figures. Show your working.  relative atomic mass = Complete the table which describes a gaseous atom of gallium. isotope nucleon number total number of electrons in lowest energy level type of orbital which contains the electron in the highest energy level 71Ga  When gallium is heated in excess chlorine, gallium trichloride, GaCl 3, is made. Draw the shape of the gallium trichloride molecule and suggest the Cl –Ga–Cl bond angle. shape of molecule bond angle  Gallium oxide, Ga2O3, and aluminium oxide react in the same way with HCl and with NaOH. Suggest the equation for the reaction between Ga2O3 and HCl . Suggest an equation for the reaction between gallium oxide and NaOH. 
22. Analytical techniques  →  22.2. Mass spectrometry
2. Atoms, molecules and stoichiometry  →  2.1. Relative masses of atoms and molecules
11. Group 17  →  11.2. The chemical properties of the halogen elements and the hydrogen halides
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Nitric acid can be made in a 3-stage process. Stage 1 Ammonia is oxidised by oxygen from the air, to form nitrogenmonoxide and water. This reaction is carried out at 10–13 atmospheres pressure and 900 °C in the presence of a platinum catalyst. Stage 2 Nitrogenmonoxide reacts with more oxygen to form nitrogendioxide. 2NO + O2 2NO2 ∆H = –114 kJ mol–1 Stage 3 Nitrogendioxide reacts with water to make nitricacid and nitrogenmonoxide. 3NO2 + H2O → 2HNO3 + NO Write an equation to show the reaction occurring in stage 1. Draw a ‘dot-and-cross’ diagram to show the arrangement of outer electrons in a molecule of ammonia.  In the boxes, give the oxidation numbers of nitrogen in the nitrogen-containing species for the reaction in stage3. 3NO2 + H2O → 2HNO3 + NO  Explain why the reaction in stage3 is described as a disproportionation reaction. Include reference to transfer of electrons in your answer. The release of nitrogenmonoxide into the atmosphere causes atmospheric pollution. State and explain the effect of nitrogenmonoxide gas in contact with moist air. The nitricacid made in stage3 can then be reacted with ammonia to form ammoniumnitrate. Stage 3 3NO2 + H2O → 2HNO3 + NO NH3 + HNO3 → NH4NO3 Calculate the volume of nitrogen dioxide, measured at room temperature and pressure, required to make 40tonnes of ammoniumnitrate. [1 tonne = 1000 kg] Show your working.  volume of nitrogen dioxide = State one use of ammonium nitrate. 
12. Nitrogen and sulfur  →  12.1. Nitrogen and sulfur
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Sucrose, C12H22O11, reacts with water to form glucose and fructose in reactionA. C12H22O11 + H2O + glucose fructose reaction A C CH2OH OH H C OH H C C OH H C H H O HO C CH2OH OH H C OH H C C H CH2OH O HO Suggest a name for this type of reaction. Explain in detail, why glucose and fructose are a pair of structural isomers. Your answer should refer specifically to these two molecules. ReactionA occurs faster in the presence of an enzyme. This is reactionB. The activation energy for reactionB is +29 kJ mol–1. Predict a value for the activation energy of reactionA. The enthalpy change for reactionA is –14 kJ mol–1. Predict a value for the enthalpy change for reactionB. Sketch a labelled energy level diagram for reactionB. Use relevant values from and . energy / kJ mol–1 progress of reaction  1.00 g of sucrose, C12H22O11, is completely combusted. The heat energy produced is used to increase the temperature of 250 g of water inside a calorimeter from 25.0 °C to 40.7 °C. These data can be used to calculate the enthalpy change of combustion of sucrose. Explain what is meant by the term enthalpy change of combustion of sucrose. Use the Data Booklet to calculate the enthalpy change, in kJ mol–1, for the combustion of sucrose. Assume that all of the heat energy produced is transferred to the water. Show your working.  enthalpy change of combustion of sucrose = kJ mol–1  
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
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An unlabelled bottle contains a straight-chain halogenoalkane, Q. The molecular formula of Q is C5H11X, where X is a halogen; bromine, chlorine or iodine. A test is carried out to identify the halogen present in Q. A sample of Q is added to NaOHand warmed. Dilute nitricacid is then added followed by a few drops of aqueous silvernitrate. A cream precipitate is observed. Suggest the identity of X. Write an ionic equation to describe the formation of the cream precipitate. Include state symbols. Describe a further test which would confirm the identity of X. test expected result  The reaction of Q with NaOHtends to proceed via an SN2 mechanism. Suggest the structural formula of the straight-chain halogenoalkane Q.  Explain why the reaction tends to proceed via an SN2 mechanism rather than an SN1 mechanism. Two different halogenoalkanes, P and R, both with the molecular formula C4H9Cl, are separately dissolved in ethanol and heated under reflux with sodium hydroxide. The major organic product of each of these reactions is methylpropene. Name the type of reaction occurring. Write an equation, using molecular formulae, to represent the reaction occurring. Draw the skeletal formula of methylpropene.  Give the names of P and R. 
15. Halogen compounds  →  15.1. Halogenoalkanes
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5
The reaction sequence shows how ethene, C2H4, can be converted into other organic molecules. C2H4 W reaction 1 reaction 2 reaction 6 reaction 3 reaction 4 heat with dilute acid OH reaction 5 O N HO Cl NH2 Complete the table to give ● ● the name of the reaction mechanisms of reactions 1 and 6 ● ● the reagents and conditions required for reactions 1, 2 and 6. reaction name of mechanism name of reagents and conditions  In reaction3 the organic molecule reacts with HCN and a KCN catalyst. Complete the diagram to show the mechanism of the reaction occurring. Include all relevant dipoles, lone pairs and curly arrows in your answer. C C C O CN H H3C H3C O H C OH CN H3C H H – C N N – C N –  Name the functional groups present in the product of reaction3. Draw the structure of the organic molecule W formed in reaction4.  
14. Hydrocarbons  →  14.2. Alkenes
13. An introduction to AS Level organic chemistry  →  13.2. Characteristic organic reactions
21. Organic synthesis  →  21.1. Organic synthesis
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