2020年11月IB化学SL真题下载-Paper2
1. Chlorine undergoes many reactions.
(a) (i) State the full electron configuration of the chlorine atom.
(ii) State, giving a reason, whether the chlorine atom or the chloride ion has a larger radius.
(iii) Outline why the chlorine atom has a smaller atomic radius than the sulfur atom.
(iv) The mass spectrum of chlorine is shown.
Outline the reason for the two peaks at m/z = 35 and 37.
(v) Explain the presence and relative abundance of the peak at m/z = 74. [2]
(b) 2.67 g of manganese(IV) oxide was added to 200.0 cm3 of 2.00 mol dm−3 HCl.
MnO2 (s) + 4HCl (aq) → Cl2 (g) + 2H2O (l) + MnCl2 (aq)
(i) Calculate the amount, in mol, of manganese(IV) oxide added.
(ii) Determine the limiting reactant, showing your calculations.
(iii) Determine the excess amount, in mol, of the other reactant.
(iv) Calculate the volume of chlorine, in dm3, produced if the reaction is conducted at standard temperature and pressure (STP). Use section 2 of the data booklet.
(v) State the oxidation state of manganese in MnO2 and MnCl2.
MnO2:
MnCl2:
(vi) Deduce, referring to oxidation states, whether MnO2 is an oxidizing or reducing agent.
(c) Chlorine gas reacts with water to produce hypochlorous acid and hydrochloric acid.
Cl2 (g) + H2O (l) ⇔ HClO (aq) + HCl (aq)
(i) Hypochlorous acid is considered a weak acid. Outline what is meant by the term weak acid.
(ii) State the formula of the conjugate base of hypochlorous acid.
(iii) Calculate the concentration of H+ (aq) in a HClO (aq) solution with a pH = 3.61.
(d) (i) State the type of reaction occurring when ethane reacts with chlorine to produce chloroethane.
(ii) Predict, giving a reason, whether ethane or chloroethane is more reactive.
(iii) Write the equation for the reaction of chloroethane with a dilute aqueous solution of sodium hydroxide.
(iv) Deduce the nucleophile for the reaction in d(iii).
(v) Ethoxyethane (diethyl ether) can be used as a solvent for this conversion.Draw the structural formula of ethoxyethane.
(vi) Deduce the number of signals and their chemical shifts in the 1H NMR spectrum of ethoxyethane. Use section 27 of the data booklet.
(e) CCl2F2 is a common chlorofluorocarbon, CFC.
(i) Calculate the percentage by mass of chlorine in CCl2F2.
(ii) Comment on how international cooperation has contributed to the lowering of CFC emissions responsible for ozone depletion.
2020年11月IB化学SL真题余下省略！
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