9701_s21_qp_21
A paper of Chemistry, 9701
Questions:
6
Year:
2021
Paper:
2
Variant:
1
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1
Ethanedioicacid, HO2CCO2H, has a relative molecular mass of 90.0. Explain what is meant by the term relative molecular mass. State the empirical formula of ethanedioicacid. Calculate how many atoms of carbon are present in 0.18 g of ethanedioicacid, HO2CCO2H. Show your working.  atoms of carbon present = Solid ethanedioic acid reacts with aqueous calcium ions to make a precipitate of calciumethanedioate, CaC2O4. CaC2O4 breaks down when heated to form calciumoxide, carbondioxide and carbonmonoxide. Construct an equation to represent the reaction of CaC2O4 when heated. Include state symbols. Identify the type of reaction which occurs when CaC2O4 is heated. Identify another compound containing calcium ions which will also produce carbondioxide and calciumoxide when it is heated. 
2. Atoms, molecules and stoichiometry  →  2.3. Formulas
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2
Carbonmonoxide gas, CO, and nitrogen gas, N2, are both diatomic molecules. The diagram shows the arrangement of outer electrons in a molecule of CO. C O State one similarity and one difference in the way the atoms in a carbon monoxide molecule are bonded together compared to the atoms in a nitrogen molecule. The table states the electronegativity values of carbon, nitrogen and oxygen atoms. C N O electronegativity 2.5 3.0 3.5 Use the electronegativity values and relevant details from the Data Booklet to complete the table below. N2 CO number of electrons per molecule typeof intermolecular (van der Waals’) force  N2is less reactive than COeven though N2has a lower bond energy than CO. Suggest why COis more reactive than N2. Both carbonmonoxide and nitrogen are gases at room temperature and pressure. They both behave like ideal gases under certain conditions. State the two conditions necessary for these two gases to approach ideal gas behaviour. Explain why N2behaves more like an ideal gas than COdoes at 20.0 °C and 101 kPa. Calculate the amount, in mol, of pure nitrogen gas which occupies 100 cm3 at 101 kPa and 20.0 °C. Use relevant information from the Data Booklet. Show your working. Assume nitrogen behaves as an ideal gas.  mol  
3. Chemical bonding  →  3.4. Covalent bonding and coordinate (dative covalent) bonding
4. States of matter  →  4.1. The gaseous state: ideal and real gases and \( pV = nRT \)
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3
Sodium halide salts react with concentrated sulfuricacid at room temperature. Write an equation to represent the reaction of NaCl with concentrated sulfuricacid. Name this type of reaction. NaIreacts with concentrated sulfuricacid, at room temperature, to form steamy fumes. Identify the chemical responsible for the steamy fumes. The reaction of NaIwith concentrated sulfuricacid continues, forming several other products, including a dark grey solid. Identify the chemical responsible for the dark grey solid and one other product of this further reaction. dark grey solid other product  Explain the differences in observations, at room temperature, when NaIreacts with concentrated sulfuricacid compared to those for NaCl . Complete the equation for the reaction of Br – with excess concentrated H2SO4 at room temperature. Br – + H+ + H2SO4 →  
11. Group 17  →  11.3. Some reactions of the halide ions
12. Nitrogen and sulfur  →  12.1. Nitrogen and sulfur
11. Group 17  →  11.4. The reactions of chlorine
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Aqueous bromine reacts with methanoicacid to form hydrogenbromide and carbondioxide gas. Br2+ HCO2H→ 2HBr+ CO2The table shows the oxidation numbers of bromine and carbon in the species involved in this reaction. Br in Br2 C in HCO2H Br in HBr C in CO2 oxidation number +2 –1 +4 Identify the oxidising agent in this reaction. Explain your reasoning with reference to oxidation numbers. Suggest one change you would observe, ignoring temperature changes, when bromine reacts with methanoicacid. This reaction can be followed by measuring the concentration of bromine present in the mixture at regular time intervals. The graph shows the change in concentration of bromine against time in a reaction carried out at 20 °C. time / s [Br2] 105 / mol dm–3 Use the graph to calculate the average rate of reaction at 20 °C during the first 600 s. State the units of this rate of reaction. average rate of reaction units  The experiment is repeated at a temperature of 40 °C. This relatively small increase in temperature produces a large increase in reaction rate. Sketch a graph, on the same axes, to show the expected results when repeating the experiment at 40 °C. The rate of reaction increases when the frequency of successful collisions between reactant particles increases. Explain why an increase in temperature produces this effect. Complete the ‘dot-and-cross’ diagram, showing outer electrons only, to show the bonding in methanoic acid, HCO2H. C O O H H  
8. Reaction kinetics  →  8.1. Rate of reaction
8. Reaction kinetics  →  8.2. Effect of temperature on reaction rates and the concept of activation energy
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Naphtha is a mixture which contains only hydrocarbon molecules. What is meant by the term hydrocarbon? Name the raw material that is used to produce a sample of naphtha. CompoundV is found in naphtha. It has a molecular formula C10H22. When V is heated at high pressure in the absence of air, an equal number of moles of ethene, propene and W are made. W is a compound made of straight chain, saturated molecules. Name the process that describes this reaction. Deduce the structure of W. Draw its structure below.  Propene is separated from the mixture and heated in air in the presence of a catalyst. Propene is oxidised to X, which contains two functional groups. Effervescence is seen when Na2CO3is added to X. Identify the functional group present in X which is responsible for this observation. Identify a reagent which could be used to show that X contains a C=C. Include relevant observations. X reacts with another reagent to form Y. Molecules of Y react together to form addition polymerZ. The diagram shows the repeat unit of polymerZ. O O– Na+ repeat unit of polymer Z Draw the structural formula of monomerY.  Polymer Z is useful because it absorbs large amounts of water. However, there are problems associated with the disposal of products containing polymer Z. Combustion is not an appropriate method to dispose of pure Z because the process releases harmful gases. Some of these gases contribute to the enhanced greenhouse effect. Identify a gas released during the combustion of Z which contributes to the enhanced greenhouse effect. Identify another gas which could be produced during the combustion of pure Z. Describe a consequence, other than the enhanced greenhouse effect, of its release into the atmosphere. gas consequence  
14. Hydrocarbons  →  14.1. Alkanes
14. Hydrocarbons  →  14.2. Alkenes
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Propene, C3H6, reacts with H2O in the presence of an acid catalyst to form an alcohol with molecular formula C3H8O. Name this type of reaction. Name the catalyst used and state the conditions needed for this reaction to occur. catalyst conditions  Complete the table to show the numbers of sigma (σ) bonds and pi (π) bonds present in propene, C3H6, and C3H8O. σ π C3H6 C3H8O  The reaction of propene, C3H6, with H2O occurs in a two-step mechanism. In step1 C3H6 reacts with the catalyst, H+, to form a carbocation. Draw structures to identify the more stable and less stable carbocations which can form in step1. Explain your answer. more stable carbocation less stable carbocation explanation  Name the major organic product formed from the reaction of propene, C3H6, with H2O. 2-bromopropane reacts to form propene, hydrogen bromide and water under certain conditions. Name this type of reaction. Describe the reagents and conditions needed to favour this reaction. reagents conditions  
14. Hydrocarbons  →  14.2. Alkenes
14. Hydrocarbons  →  14.1. Alkanes
18. Carboxylic acids and derivatives  →  18.2. Esters
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