A-level CHEMISTRY Paper 1 Inorganic and Physical Chemistry 2 *02* IB/M/Jun22/7405/1

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A-level CHEMISTRY Paper 1 Inorganic and Physical Chemistry 2 *02* IB/M/Jun22/7405/1 Do not write outside the There are no questions printed on this page box DO NOT WRITE ON THIS PAGE ANSWE... R IN THE SPACES PROVIDED 3 *03* Turn over ► IB/M/Jun22/7405/1 Do not write outside the Answer all questions in the spaces provided. box 0 1 This question is about equilibria. 0 1 . 1 Give two features of a reaction in dynamic equilibrium. [2 marks] Feature 1 Feature 2 0 1 . 2 A gas-phase reaction is at equilibrium. When the pressure is increased the yield of product decreases. State what can be deduced about the chemical equation for this equilibrium. [1 mark] Question 1 continues on the next page 4 *04* IB/M/Jun22/7405/1 Do not write outside the box 0 1 . 3 Carbon monoxide and hydrogen react to form methanol. CO(g) + 2H2(g) ⇌ CH3OH(g) 0.430 mol of carbon monoxide is mixed with 0.860 mol of hydrogen. At equilibrium, the total pressure in the flask is 250 kPa and the mixture contains 0.110 mol of methanol. Calculate the amount, in moles, of carbon monoxide present at equilibrium. Calculate the partial pressure, in kPa, of carbon monoxide in this equilibrium mixture. [3 marks] Amount of carbon monoxide mol Partial pressure kPa 0 1 . 4 Give an expression for the equilibrium constant (Kp) for this reaction. CO(g) + 2H2(g) ⇌ CH3OH(g) [1 mark] Kp 5 *05* Turn over ► IB/M/Jun22/7405/1 Do not write outside the box 0 1 . 5 A different mixture of carbon monoxide and hydrogen is left to reach equilibrium at a temperature T. Some data for this equilibrium are shown in Table 1. Table 1 Partial pressure of CO 125 kPa Partial pressure of CH3OH 5.45 kPa Kp 1.15 x 10–6 kPa–2 CO(g) + 2H2(g) ⇌ CH3OH(g) Calculate the partial pressure, in kPa, of hydrogen in this equilibrium mixture. [3 marks] Partial pressure kPa 0 1 . 6 Use the Kp value from Table 1 to calculate a value for Kp for the following reaction at temperature T. CH3OH(g) ⇌ CO(g) + 2H2(g) Give the units for Kp [2 marks] Kp Units 12 6 *06* IB/M/Jun22/7405/1 Do not write outside the box 0 2 Rhenium has an atomic number of 75 0 2 . 1 Define the term relative atomic mass. [2 marks] 0 2 . 2 The relative atomic mass of a sample of rhenium is 186.3 Table 2 shows information about the two isotopes of rhenium in this sample. Table 2 Relative isotopic mass Relative abundance 185 10 To be calculated 17 Calculate the relative isotopic mass of the other rhenium isotope. Show your working. [2 marks] Relative isotopic mass 0 2 . 3 State why the isotopes of rhenium have the same chemical properties. [1 mark] 7 *07* Turn over ► IB/M/Jun22/7405/1 Do not write outside the box A sample of rhenium is ionised by electron impact in a time of flight (TOF) mass spectrometer. 0 2 . 4 A 185Re+ ion with a kinetic energy of 1.153 × 10−13 J travels through a 1.450 m flight tube. The kinetic energy of the ion is given by the equation KE = 1 2 mv 2 where m = mass / kg v = speed / m s–1 KE = kinetic energy / J Calculate the time, in seconds, for the ion to reach the detector. The Avogadro constant, L = 6.022 × 1023 mol−1 [5 marks] Time s 8 *08* IB/M/Jun22/7405/1 Do not write outside the box 0 2 . 5 State how the relative abundance of 185Re+ is determined in a TOF mass spectrometer. [2 marks] 12 9 *09* Turn over ► IB/M/Jun22/7405/1 Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 10 *10* IB/M/Jun22/7405/1 Do not write outside the box 0 3 This question is about hydrogen peroxide, H2O2 The half-equation for the oxidation of hydrogen peroxide is H2O2  O2 + 2H+ + 2e– Hair bleach solution contains hydrogen peroxide. A sample of hair bleach solution is diluted with water. The concentration of hydrogen peroxide in the diluted solution is 5.00% of that in the original solution. A 25.0 cm3 sample of the diluted hair bleach solution is acidified with dilute sulfuric acid. This acidified sample is titrated with 0.0200 mol dm−3 potassium manganate(VII) solution. The reaction is complete when 35.85 cm3 of the potassium manganate(VII) solution are added. 0 3 . 1 Give an ionic equation for the reaction between potassium manganate(VII) and acidified hydrogen peroxide. Calculate the concentration, in mol dm–3, of hydrogen peroxide in the original hair bleach solution. (If you were unable to write an equation for the reaction you may assume that the mole ratio of potassium manganate(VII) to hydrogen peroxide is 3:4 This is not the correct mole ratio.) [5 marks] Concentration mol dm–3 11 *11* Turn over ► IB/M/Jun22/7405/1 Do not write outside the box 0 3 . 2 State why an indicator is not added in this titration. [1 mark] 0 3 . 3 Give the oxidation state of oxygen in hydrogen peroxide. [1 mark] 0 3 . 4 Hydrogen peroxide decomposes to form water and oxygen. Give an equation for this reaction. Calculate the amount, in moles, of hydrogen peroxide that would be needed to produce 185 cm3 of oxygen gas at 100 kPa and 298 K The gas constant, R = 8.31 J K−1 mol−1 [5 marks] Equation Amount mol 12 *12* IB/M/Jun22/7405/1 Do not write outside the box 0 3 . 5 Hydrazine (N2H4) is used as a rocket fuel that is oxidised by hydrogen peroxide. The equation for this reaction in the gas phase is The enthalpy change for this reaction, ∆H = –789 kJ mol−1 Table 3 shows some mean bond enthalpy values. Table 3 N–H N–N N≡N O–H Mean bond enthalpy / kJ mol−1 388 163 944 463 Define the term mean bond enthalpy. Use the equation and the data in Table 3 to calculate a value for the O–O bond enthalpy in hydrogen peroxide. [5 marks] Definition Bond enthalpy kJ mol–1 17 13 *13* Turn over ► IB/M/Jun22/7405/1 Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 14 *14* IB/M/Jun22/7405/1 Do not write outside the box 0 4 This question is about acids and bases. 0 4 . 1 Calculate the pH of a 0.150 mol dm–3 solution of ethanoic acid at 25 oC Give your answer to 2 decimal places. For ethanoic acid, Ka = 1.74 x 10–5 mol dm–3 at 25 o [Show More]

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