CAIE
Chemistry
(9701)
Questions & Answers
Gallium is an element in Group 13. A sample of gallium is analysed using a mass spectrometer. The mass spectrum produced is shown. % relative abundance mass 6971 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 [3] , is made. shape of molecule bond angle
Gallium oxide, Ga NaOH(aq).
Suggest the equation for the reaction between Ga
Suggest an equation for the reaction between gallium oxide and NaOH(aq). [Total: 12]
Nitric acid can be made in a 3-stage process. Stage 1 Ammonia is oxidised by oxygen from the air, to form nitrogen monoxide and water. This platinum catalyst. Stage 2 Nitrogen monoxide reacts with more oxygen to form nitrogen dioxide. 2NO + O 2NO Stage 3 Nitrogen dioxide reacts with water to make nitric acid and nitrogen monoxide.3NO + H + 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.
(i) In the boxes, give the oxidation numbers of nitrogen in the nitrogen-containing species for the reaction in stage 3.3NO + H + NO
Explain why the reaction in stage 3 is described as a disproportionation reaction. Include reference to transfer of electrons in your answer.
The release of nitrogen monoxide into the atmosphere causes atmospheric pollution. State and explain the effect of nitrogen monoxide gas in contact with moist air.
The nitric acid made in stage 3 can then be reacted with ammonia to form ammonium nitrate. Stage 3 3NO + H + NO + HNO Calculate the volume of nitrogen dioxide, measured at room temperature and pressure, required to make 40 tonnes of ammonium nitrate. Show your working. volume of nitrogen dioxide =
State one use of ammonium nitrate. [Total: 12] 3 Sucrose, C , reacts with water to form glucose and fructose in reaction A. + H glucose fructose reaction AOHH COHHOHHOHH COHHOHO
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.
Reaction A occurs faster in the presence of an enzyme. This is reaction B. Predict a value for the activation energy of reaction A. Predict a value for the enthalpy change for reaction B.
Sketch a labelled energy level diagram for reaction B. Use relevant values from (c)(i) and
(ii). energy / kJ mol progress of reaction [2] , is completely combusted. The heat energy produced is used to 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 . , for the combustion of sucrose. Assume that all of the heat energy produced is transferred to the water. Show your working. [3] [Total: 12]
An unlabelled bottle contains a straight-chain halogenoalkane, Q. The molecular formula of Q is C X, 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 NaOH(aq) and warmed. Dilute nitric acid is then added followed by a few drops of aqueous silver nitrate. 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 NaOH(aq) tends to proceed via an S 2 mechanism.
Suggest the structural formula of the straight-chain halogenoalkane Q.
Explain why the reaction tends to proceed via an S 2 mechanism rather than an S mechanism.
Two different halogenoalkanes, P and R, both with the molecular formula C Cl, 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. [Total: 12]
The reaction sequence shows how ethene, C , can be converted into other organic molecules. reaction 1 reaction 2 reaction 6 reaction 3 reaction 4 heat with dilute acid reaction 5
Complete the table to give reaction name of mechanism name of reagents and conditions
In reaction 3 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.COH
Name the functional groups present in the product of reaction 3.
Draw the structure of the organic molecule W formed in reaction 4. [1] [Total: 12] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.