9701_s18_qp_23
A paper of Chemistry, 9701
Questions:
4
Year:
2018
Paper:
2
Variant:
3
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1
The elements sodium to chlorine, in the third period, all form oxides. Draw a diagram to show the shape of the molecule of each of the oxides, SO3 and Cl 2O. Name each shape. In SO3 each oxygen atom forms a double bond with the sulfur atom. SO3 Cl 2O  Explain why the melting point of MgO is higher than that of Na2O. Explain why the melting point of SiO2 is much higher than that of SO3. SO3 is produced by the reaction between SO2 and O2 in the Contact process. A dynamic equilibrium is established. 2SO2+ O22SO3∆H = –196 kJ mol–1 Explain why increasing the total pressure, at constant temperature, increases the rate of production of SO3 and increases the yield of SO3. rate yield  The graph shows how the concentrations of all three species in the system change with time for a typical reaction mixture. The gradients of all three lines decrease with time and then level off in this dynamic equilibrium. time concentration concentration of SO3 concentration of SO2 concentration of O2 Explain why the gradients of the SO2 and O2 lines decrease with time. Explain why all three lines become horizontal. Suggest a reason why the initial gradient of the SO2 line is steeper than that of the O2 line. 2.00moles of SO2and 2.00moles of O2are sealed in a container with a suitable catalyst, at constant temperature and pressure. The resulting equilibrium mixture contains 1.98moles of SO3. The total volume of the equilibrium mixture is 40.0 dm3. 2SO2+ O22SO3Write the expression for the equilibrium constant, Kc, for the reaction between SO2and O2to produce SO3. Kc =  Calculate the amount, in moles, of SO2and O2in the equilibrium mixture.  SO2= mol  O2= mol  Use your answers to and to calculate the value of Kc for this equilibrium mixture. Give the units of Kc.  Kc =  units =  
7. Equilibria  →  7.1. Chemical equilibria: reversible reactions, dynamic equilibrium
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One reason for the wide variety of organic compounds is isomerism, either structural isomerism or stereoisomerism. Explain the meaning of the term structural isomerism. Explain the meaning of the term stereoisomerism. Pent-1-ene, CH2=CH(CH2)2CH3, does not show stereoisomerism. Give two reasons why pent-1-ene does not show stereoisomerism. reason 1 reason 2  A structural isomer of pent-1-ene is used as the monomer to form a polymer. The repeat unit of this polymer is shown. C H H C CH3 CH2CH3 Draw the displayed formula of the monomer used to make this polymer. Give the name of the monomer.  A different structural isomer of pent-1-ene shows geometrical isomerism. Draw the structure of one of the two geometrical isomers with the formula C5H10. Give the full name of this isomer.  
13. An introduction to AS Level organic chemistry  →  13.4. Isomerism: structural isomerism and stereoisomerism
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The elements in Group 17, the halogens, show trends in both their chemical and physical properties. The elements and their compounds have a wide variety of uses. At room temperature fluorine and chlorine are gases, bromine is a liquid and iodine is a solid. State the trend in the volatility of the Group 17 elements down the group. Explain this trend. Iodine, I2, can be displaced from NaI, by chlorine, Cl 2. Write an equation for this reaction. Silver nitrate solution, AgNO3, is added to separate solutions of NaI and NaCl. Precipitates form. An excess of aqueous ammonia is then added to both precipitates. Complete the table to give the colour and name of the precipitate formed in each reaction and the effect of the addition of an excess of aqueous ammonia to each of the precipitates formed. NaI+ AgNO3NaCl + AgNO3colour of precipitate name of precipitate effect of addition of an excess of aqueous ammonia to the precipitate  Write an ionic equation, including state symbols, to show the reaction occurring when AgNO3is added to NaI. Solid NaI reacts with concentrated sulfuric acid to form purple fumes of I2and hydrogensulfide gas, H2S. However, when solid NaCl reacts with concentrated sulfuricacid the only gas produced is HCl . Explain the difference in the reactions of concentrated sulfuricacid with NaI and with NaCl. Your answer should refer to the role of the sulfuric acid in each reaction. Chlorine is commonly used in water purification. When chlorine is added to water it reacts to produce a mixture of acids, one of which is chloric(acid, HCl O, a powerful oxidising agent. Explain the meaning of the term oxidising agent, in terms of electron transfer. Suggest an equation for this reaction of chlorine with water. Write an equation for the reaction of chlorine with hot aqueous sodiumhydroxide. Use oxidation numbers to explain why this is a redox reaction. equation 
11. Group 17  →  11.1. Physical properties of the Group 17 elements
11. Group 17  →  11.4. The reactions of chlorine
11. Group 17  →  11.3. Some reactions of the halide ions
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A is CH3CHBrCH2CH3. Some reactions of A are shown. CH3CHBrCH2CH3 H+ / Cr2O7 2– CH3CH(OH)CH2CH3 C4H8 A C4H8O B reaction 2 NaOH reaction 1 NaOH Name A. Name the class of compound to which B belongs. There are three structural isomers of A. Draw the structures of these three isomers of A.  Reaction1 occurs by two different mechanisms at the same time. These mechanisms are referred to as SN1 and SN2. State what the letters ‘S’ and ‘N’ represent in the abbreviation SN1. S N  Complete the SN1 mechanism for reaction1. Include the structure of the intermediate and all necessary charges, dipoles, lone pairs and curly arrows. CH3 H3C CH2 C Br H CH3 H3C CH2 C OH H  The SN1 mechanism for reaction1 is repeated using CH3CHCl CH2CH3 or CH3CHICH2CH3 in place of the CH3CHBrCH2CH3. State and explain how the rates of these two reactions will compare with the rate of the original reaction using CH3CHBrCH2CH3. Reaction2 uses the same reagent as reaction1, but under different conditions. State two differences in the conditions needed to ensure that reaction2 is more likely to take place than reaction1 when this reagent is added. 
15. Halogen compounds  →  15.1. Halogenoalkanes
13. An introduction to AS Level organic chemistry  →  13.2. Characteristic organic reactions
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