9701_m21_qp_22 - revisedeck

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The rate of chemical reactions is affected by changes in temperature and pressure. Draw a curve on the axes to show the Boltzmann distribution of energy of particles in a sample of gaseous krypton atoms at a given temperature. Label the curve T1 and label the axes. On the diagram in , draw a second curve to show the distribution of energies of the krypton atoms at a higher temperature. Label the second curve T2. The Boltzmann distribution assumes that the particles behave as an ideal gas. State two assumptions of the kinetic theory as applied to an ideal gas. 2.00 g of krypton gas, Kr, is placed in a sealed 5.00 dm3 container at 120 °C. Calculate the pressure, in Pa, of Krin the container. Assume Krbehaves as an ideal gas. Show your working. pressure = Pa State and explain the conditions at which krypton behaves most like an ideal gas. Krypton reacts with fluorine in the presence of ultraviolet light to make krypton difluoride, KrF2. Kr+ F2→ KrF2activation energy for the reaction, Ea = +385 kJ mol–1 enthalpy change of formation of KrF2, ∆Hf = +60.2 kJ mol–1 Use this information to complete the reaction profile diagram for the formation of KrF2. Label Ea and ∆Hf on the diagram. Assume the reaction proceeds in one step. energy / kJ mol–1 progress of reaction reactants Explain, in terms of activation energy, Ea, and the collision of particles, how an increase in temperature affects the rate of a chemical reaction.

8. Reaction kinetics → 8.2. Effect of temperature on reaction rates and the concept of activation energy

4. States of matter → 4.1. The gaseous state: ideal and real gases and \( pV = nRT \)

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Chlorine, Cl 2, is a reactive yellow-green gas. It is a strong oxidising agent. State how Cl 2 is used in water purification. Chlorine has the highest first ionisation energy of the Period3 elements Na to Cl. Construct an equation for the first ionisation energy of chlorine. Include state symbols. Explain the general increase in the first ionisation energies of the Period3 elements. The halide ions, X– (where X = Cl, Br, , show clear trends in their physical and chemical properties. State and explain the relative thermal stabilities of the hydrogen halides, HX. The halide ions react easily with concentrated H2SO4. The main sulfur-containing product of each reaction is shown in the table. halide ion Cl – Br – I– main sulfur-containing product of reaction with concentrated H2SO4 HSO4 – SO2 H2S oxidation number of sulfur Complete the table to show the oxidation number of sulfur in each of the sulfur-containing products. Explain why different sulfur-containing products are produced when each of these halide ions reacts with concentrated H2SO4. Cl 2 reacts with aqueous sodium hydroxide in a disproportionation reaction. State what is meant by disproportionation. Write an equation for the reaction of Cl 2 with cold aqueous sodium hydroxide. Aluminium reacts with chlorine to form aluminium chloride. Aluminium chloride can exist as the gaseous molecule Al 2Cl 6. This molecule contains coordinate bonds. Draw a diagram that clearly shows all the types of bond present in Al 2Cl 6. Describe what you would see when solid aluminium chloride reacts with water. Name the type of reaction that occurs. 0.020 mol of elementZ reacts with excess Cl 2 to form 0.020 mol of a liquid chloride. The liquid chloride has formula ZCl n, where n is an integer. ZCl n reacts vigorously with water at room temperature to give an acidic solution and a white solid. When excess AgNO3is added to the solution, 11.54 g of AgCl forms. Suggest the type of bonding and structure shown by ZCl n. Calculate the value of n in ZCl n. n = Dichloromethane, CH2Cl 2, is widely used as an organic solvent. CH2Cl 2 can be prepared by reacting CH3Cl and Cl 2 at room temperature. The reaction proceeds via several steps, as shown. initiation Cl 2 2Cl • propagation 1 Cl • + CH3Cl HCl + •CH2Cl propagation 2 Cl 2 + •CH2Cl products final step Cl • + •CH2Cl CH2Cl 2 Give the name of the mechanism of this reaction. State the essential condition required for the initiation step to take place. Give the electronic configuration of Cl •. 1s2 Identify the products of the step labelled propagation2. Name the type of reaction shown in the final step. Suggest the identity of another organic molecule that is a product of the reaction of CH3Cl and Cl 2 under the same conditions.

11. Group 17 → 11.4. The reactions of chlorine

9. The Periodic Table: chemical periodicity → 9.2. Periodicity of chemical properties of the elements in Period 3

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Compounds P, Q and R have all been found in the atmosphere of one of Saturn’s moons. P C C N C C N Q C C H C N C H H H C N C R The equation for the complete combustion of P, C4N2, is shown. C4N2+ 4O2→ 4CO2+ N2∆H = –2036 kJ mol–1 The enthalpy change of formation, ∆Hf, of CO2is –384 kJ mol–1. Calculate the enthalpy change of formation, ∆Hf, of P, in kJ mol–1. ∆Hf of P = kJ mol–1 One of the products of the complete combustion of P is nitrogen gas, N2. Explain the lack of reactivity of nitrogen. Q forms when HCN reacts with ethyne, H C C H. Ethyne, HCN and Q are all weak Brønsted–Lowry acids. Explain what is meant by the term weak Brønsted–Lowry acid. Ethyne, HCN and Q all contain triple bonds between two atoms. A triple bond consists of one sigma (σ) and two pi (π) bonds. Draw a labelled diagram to show the formation of one pi (π) bond. P and Q can be detected in the atmosphere by infrared spectroscopy. Identify two absorptions, and the bonds that correspond to these absorptions, that will appear in the infrared spectra of both P and Q. The flow chart shows some reactions of R. C H H H reaction 1 C N C R T CH3CH2CH2NH2 C C S H H H C N reaction 3 H2reaction 2 dilute H2SO4heat under reflux Name the type of reaction shown in reaction1. Draw the structure of S, the organic product of reaction2. Name T. T can also be formed by the reaction of CH3CH2CH2Br with ammonia. State the necessary conditions of this reaction.

11. Group 17 → 11.2. The chemical properties of the halogen elements and the hydrogen halides

12. Nitrogen and sulfur → 12.1. Nitrogen and sulfur

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Hydroxyethanal, HOCH2CHO, has been observed in dust clouds near the centre of our galaxy. hydroxyethanal C HO C O H H H Predict the bond angles labelled x and y in the diagram of hydroxyethanal. C HO C O H H H x y x = ° y = ° Hydroxyethanal reacts separately with 2,4-dinitrophenylhydrazine (2,4-DNPH) and with Tollens’ reagent. State what you would observe in each reaction. reaction with 2,4-DNPH reaction with Tollens’ reagent Hydroxyethanal is converted to ethanedioic acid, (CO2H)2, when it reacts with excess acidified dichromate(ions, Cr2O7 2–. State the role of acidified Cr2O7 2– in this reaction. State and explain any other necessary conditions for this reaction to be successful. Hydroxyethanal can be reduced to ethane-1,2-diol, (CH2OH)2, as shown. hydroxyethanal C HO C O [H] H H H ethane-1,2-diol C HO C OH H H H H Write an equation for the reduction of hydroxyethanal to (CH2OH)2. Use [H] to represent an atom of hydrogen from the reducing agent. Identify a reagent for this reduction reaction. (CH2OH)2 also forms when an alkeneA reacts with cold, dilute, acidified manganate(ions. Name A.

15. Halogen compounds → 15.1. Halogenoalkanes

17. Carbonyl compounds → 17.1. Aldehydes and ketones

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