9701_w06_qp_4
A paper of Chemistry, 9701
Questions:
5
Year:
2006
Paper:
4
Variant:
0
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1
Describe and explain how the boiling points of the tetrachlorides of the Group IV elements vary down the group. The tetrachlorides are all covalent compounds. Draw a diagram showing the shape of a molecule of silicon tetrachloride, including values for bond angles. The noble gas xenon forms a tetrafluoride, XeF4. Only four of xenon’s outer shell electrons are used in bonding to the fluorine atoms. Draw a dot-and-cross diagram showing how the outer-shell electrons are arranged in XeF4. Predict the shape and the bond angles in XeF4. Describe and explain how the reactions of CCl4 and SiCl4 with water differ. Write an equation for any reaction that occurs. Use [T Many tonnes of lead tetrachloride used to be produced to make the anti-knock petrol additive tetraethyl-lead, Pb(C2H5)4, by the following reaction. PbCl4 + ………… Na + ………… C2H5Cl ⎯⎯→ Pb(C2H5)4 + ………… NaCl Balance this equation and use it to calculate the mass of sodium needed to produce 1.0 kg of tetraethyl-lead. Examiner s Use
11. Group 17  →  11.2. The chemical properties of the halogen elements and the hydrogen halides
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
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2
Ibuprofen is one of the most commonly used non-steroidal anti-inflammatory drugs, used to treat chronic arthritic pain caused by inflammation of the joints. ibuprofen Draw a circle around any chiral centrein the above structure. Write down the molecular formula of ibuprofen. Calculate the Mr of ibuprofen and use it to calculate how many grams are needed to make 100 cm3 of a 0.15 mol dm–3 solution. Vigorous oxidation of ibuprofen produces a dibasic acid A. A solution containing 0.10 g of A required 12.0 cm3 of 0.10 mol dm–3 NaOH for neutralisation. Suggest a structure for A, showing your working. The Ka value for ibuprofen is 6.3 ×10–6mol dm–3. Write an expression for Ka. Use the Ka value to calculate the pH of a 0.15 mol dm–3 solution of ibuprofen. Use CH CH2 CH3 CH3 C O CH OH CH3 [T To avoid problems with digestive irritation over a long period of use, research is being carried out into ways of administering ibuprofen using skin patches. For this use the compound is dissolved in a hydrophilic gel which acts as a buffer. What do you understand by the term buffer? The buffer used in the pharmaceutical preparation is a solution containing Na2HPO4 and NaH2PO4. These salts contain the HPO4 2– and H2PO4 – ions respectively. Write equations to show how this buffer reacts with H+ ions, OH– ions. A buffer solution containing equal concentrations of the two sodium phosphate salts has a pH of 7.20. Calculate the pH of a pharmaceutical preparation containing 0.002 mol dm–3 of Na2HPO4 and 0.005 mol dm–3 of NaH2PO4. Examiner s Use
7. Equilibria  →  7.2. Brønsted–Lowry theory of acids and bases
2. Atoms, molecules and stoichiometry  →  2.3. Formulas
18. Carboxylic acids and derivatives  →  18.1. Carboxylic acids
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3
Write an equation showing the thermal decomposition of calcium nitrate, Ca(NO3)2. State and explain how the thermal stabilities of the nitrates vary down Group II. The nitrates of calcium, strontium or barium are often added to firework mixtures to produce red or green flames. The equation for the decomposition of one such mixture is as follows. Sr(NO3)2+ 3C⎯→SrO+ N2+ 2CO2+ COCalculate the volume of gas given off (measured at room temperature and pressure) when a 10.0 g sample of this mixture decomposes. [Mr: Sr(NO3)2, 211.6] Explain in detail how carbon monoxide, produced in this reaction, is poisonous. Use
10. Group 2  →  10.1. Similarities and trends in the properties of the Group 2 metals, magnesium to barium, and their compounds
2. Atoms, molecules and stoichiometry  →  2.4. Reacting masses and volumes (of solutions and gases)
12. Nitrogen and sulfur  →  12.1. Nitrogen and sulfur
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4
Ethylbenzene is an important starting material for making polystyrene (poly). State the conditions needed to carry out reaction I in the laboratory. State the reagent and conditions needed for reaction II. Draw the structure of the repeat unit of polystyrene. There are several polymers that consist of phenylethene co-polymerised with other monomers. The following formula shows part of the chain of one such co-polymer. Deduce the structural formula of the other monomer. CH CH2 CH2 CH CN CH2 CH CN CH2 Use CH2CH3 + Cl 2 reaction I CHCl CH3 reaction II CH CH2 polystyrene ethylbenzene B phenylethene [T Compound B undergoes the following series of reactions. Suggest reagents and conditions for reaction III. What would you see when reaction IV was carried out? Draw structures for C and D in the boxes above. Ethylbenzene can react with chlorine under a different set of conditions to give compound E, an isomer of compound B. Compound E undergoes the following reaction. Draw a structure for E in the box above. Describe the conditions used for reaction V. State the reagents used for reaction VI. Examiner s Use + CHCl CH3 reaction III B C D CH(OH)CH3 reaction IV I2 + NaOH CH2CH3 + Cl2 Cl reaction V CO2H reaction VI E
14. Hydrocarbons  →  14.2. Alkenes
20. Polymerisation  →  20.1. Addition polymerisation
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5
Use 4-Amino-1-methylbenzene, F, is a useful starting material for making several dyes. The following chart shows some of its reactions. Suggest reagents and conditions for reaction I. Draw the structural formulae of compounds G and H in the boxes above. Name the functional group you have drawn in compound G. CH3 CH3 NH2 Br Br NH2 + CH3COCl + HCl reaction II reaction I reaction III H G F The dye J can be made from F by the following series of reactions. Suggest reagents and conditions for reaction IV, reaction V. Many dyestuffs used as food colourings, such as Sunset Yellow, contain sodium sulphonate (–SO3 –Na+) groups attached to the rings. Suggest, with an explanation, a reason for this. N N SO 3 Na+ Sunset Yellow SO 3 Na+ HO – – H3C NH2 reaction IV reaction V H3C N2Cl H3C H3C CH3 N N OH F J Examiner s Use
21. Organic synthesis  →  21.1. Organic synthesis
16. Hydroxy compounds  →  16.1. Alcohols
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