2018年11月IB化学SL真题下载-Paper2
1. 3.26 g of iron powder are added to 80.0 cm3 of 0.200 mol dm−3 copper(II) sulfate solution. The following reaction occurs:
Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
(a) (i) Determine the limiting reactant showing your working.
(ii) The mass of copper obtained experimentally was 0.872 g. Calculate the percentage yield of copper.
(b) (i) The reaction was carried out in a calorimeter. The maximum temperature rise of the solution was 7.5 °C.Calculate the enthalpy change, ΔH, of the reaction, in kJ, assuming that all the heat released was absorbed by the solution. Use sections 1 and 2 of the data booklet.
(ii) State another assumption you made in (b)(i).
(iii) The only significant uncertainty is in the temperature measurement.
Determine the absolute uncertainty in the calculated value of ΔH if the uncertainty in the temperature rise was ±0.2 °C.
(c) (i) Sketch a graph of the concentration of iron(II) sulfate, FeSO4, against time as the reaction proceeds.
(ii) Outline how the initial rate of reaction can be determined from the graph in part (c)(i).
(iii) Explain, using the collision theory, why replacing the iron powder with a piece of iron of the same mass slows down the rate of the reaction.
2. Propan-2-ol is a useful organic solvent.
(a) Draw the structural formula of propan-2-ol.
(b) Calculate the number of hydrogen atoms in 1.00 g of propan-2-ol.
(c) Classify propan-2-ol as a primary, secondary or tertiary alcohol, giving a reason.
(d) (i) State a suitable oxidizing agent for the oxidation of propan-2-ol in an acidified aqueous solution.
(ii) Deduce the average oxidation state of carbon in propan-2-ol.
(iii) Deduce the product of the oxidation of propan-2-ol with the oxidizing agent in (d)(i).
3. Bromine can form the bromate(V) ion, BrO3−.
(a) (i) State the electron configuration of a bromine atom.
(ii) Sketch the orbital diagram of the valence shell of a bromine atom (ground state) on the energy axis provided. Use boxes to represent orbitals and arrows to represent electrons.
(b) Draw the Lewis (electron dot) structure for BrO3− that obeys the octet rule.
(c) Predict, using the VSEPR theory, the geometry of the BrO3− ion and the O−Br−O bond angles.
Geometry:
Reason:
O−Br−O angle:
(d) (i) Bromate(V) ions act as oxidizing agents in acidic conditions to form bromide ions.Deduce the half-equation for this reduction reaction.
(ii) Bromate(V) ions oxidize iron(II) ions, Fe2+, to iron(III) ions, Fe3+.Deduce the equation for this redox reaction.
2018年11月IB化学SL真题余下省略！
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