9701_w15_qp_22
A paper of Chemistry, 9701
Questions:
4
Year:
2015
Paper:
2
Variant:
2
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1
Fill the gaps in the table for each of the given particles. name of isotope type of particle charge symbol electron confi guration carbon-13 1s22s22p2 –1 Cl – sulfur-34 atom iron-54 cation 1s22s22p63s23p63d6 One of the factors that determines the type of bonding present between the particles of a substance is the relative electronegativities of the bonded particles. Explain the meaning of the term electronegativity. Name and describe the type of bonding you would expect to fi nd between particles with equal electronegativities. Name and describe the type of bonding you would expect to fi nd between particles with very different electronegativities. The boiling points of some molecules with equal numbers of electrons are given. substance fl uorine argon hydrogen chloride methanol formula F2 Ar HCl CH3OH boiling point / K Explain why the boiling points of fl uorine and argon are so similar. Explain why the boiling point of hydrogen chloride is higher than that of fl uorine. Explain why methanol has the highest boiling point of all these molecules.
3. Chemical bonding  →  3.1. Electronegativity and bonding
3. Chemical bonding  →  3.6. Intermolecular forces, electronegativity and bond properties
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2
Chemical reactions are accompanied by enthalpy changes. Explain the meaning of the term standard enthalpy change of reaction. The enthalpy change of hydration of anhydrous magnesium sulfate, ∆Hhyd MgSO4, can be calculated by carrying out two separate experiments. In the fi rst experiment 45.00 g of water was weighed into a polystyrene cup and 3.01 g of MgSO4 was added and stirred until it was completely dissolved. The temperature of the water rose from 23.4 °C to 34.7 °C. Calculate the amount of heat energy transferred to the water during this dissolving process. You can assume that the specifi c heat capacity of the solution is the same as that of water, 4.18 J g–1 K–1. heat energy = J Calculate the amount, in moles, of MgSO4 dissolved. amount = mol Calculate the enthalpy change of solution, ∆Hsoln, of MgSO4. You must include a sign with your answer. ∆Hsoln, of MgSO4= kJ mol–1 In the second experiment, the enthalpy change of solution for the hydrated salt, MgSO4.7H2O, was calculated and found to be +9.60 kJ mol–1. Use the equation below for the hydration of anhydrous magnesium sulfate to construct a suitable, fully labelled energy cycle that will allow you to calculate the enthalpy change for this reaction, ∆Hhyd MgSO4. MgSO4+ 7H2O→ MgSO4.7H2O Calculate the enthalpy change for this reaction, ∆Hhyd MgSO4. Include a sign in your answer. ∆Hhyd MgSO4 = kJ mol–1
5. Chemical energetics  →  5.1. Enthalpy change, \(\Delta H\)
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3
The elements in Period 3, Na, Mg, Al, P and S, all react with oxygen when heated in air. Give the formula of the oxide formed when each element is heated in air. One has been completed for you. Na = Mg = Al = Al 2O3 P = S = Describe what you would see when sodium and sulfur are each heated separately in air and give an equation for each reaction. Na equation S equation The oxides show variations in their behaviour when added to water, acids and alkalis. Place the symbols of the elements in in the appropriate row of the table to indicate this behaviour. acidic amphoteric basic State the bonding present in acidic and basic oxides. acidic basic Write equations for the reaction of aluminium oxide with each of hydrochloric acid, HCl, and sodium hydroxide, NaOH. with HCl with NaOH Explain how the presence of an impurity in carbonaceous fuels can give rise to acid rain. name of impurity
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
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4
Halogenoalkanes are useful intermediates in the synthesis of a wide variety of compounds. 2-bromobutane reacts in two different ways with sodium hydroxide depending on the conditions. When warmed with aqueous sodium hydroxide, 2-bromobutane produces an alcohol that exists as a pair of optical isomers. Give the name of the mechanism of the reaction between 2-bromobutane and aqueous sodium hydroxide. Explain why the alcohol produced exists as a pair of optical isomers. Draw the three-dimensional structure of the two optical isomers of the alcohol produced in . Heating 2-bromobutane with ethanolic sodium hydroxide produces a mixture of three alkenes, two of which are a pair of geometrical isomers. Give the name of the mechanism of the reaction between 2-bromobutane and ethanolic sodium hydroxide. Draw and name the structures of the pair of geometrical isomers formed by reaction of 2-bromobutane with ethanolic sodium hydroxide. name name Name the third alkene produced by reaction of 2-bromobutane with ethanolic sodium hydroxide and explain why it does not show geometrical isomerism. Some reactions involving 2-bromopropane are shown. CH3CHBrCH3 2-bromopropane CH3CH2CO2H (and CH3CH(NH2)CH3 which is removed) CH3CH2CH2OH CH3CH(NH2)CH3 X Y reaction 1 reaction 2 reaction 5 reaction 4 reaction 3 hydrolysis reaction 6 HBr State the reagent needed for reaction 1. State the reagent needed for reaction 2. Give the structural formula of X. Name the type of reaction involved in reaction 4 and suggest a suitable reagent. State the name of a solid catalyst for reaction 5. Complete the mechanism for the production of 2-bromopropane from Y in reaction 6 shown below. Include the structure of Y and any necessary lone pairs, curly arrows, charges and partial charges. Y H Br intermediate H3C CH3 C H Br Give the name of the mechanism in . 1-bromopropane is a minor product of reaction 6. Explain why 2-bromopropane is the major product of reaction 6.
15. Halogen compounds  →  15.1. Halogenoalkanes
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