2017年5月IB化学SL真题下载-Paper2
1. The rate of the acid-catalysed iodination of propanone can be followed by measuring how the concentration of iodine changes with time.
I2 (aq) + CH3COCH3 (aq) → CH3COCH2I (aq) + H+ (aq) + I− (aq)
(a) (i) Suggest how the change of iodine concentration could be followed.
(ii) A student produced these results with [H+ ] = 0.15 mol dm−3. Propanone and acid were in excess and iodine was the limiting reagent.
Determine the relative rate of reaction when [H+ ] = 0.15 mol dm−3.
(b) The student then carried out the experiment at other acid concentrations with all other conditions remaining unchanged.
State and explain the relationship between the rate of reaction and the concentration of acid.
2. Titanium is a transition metal.
(a) Describe the bonding in metals.
(b) Titanium exists as several isotopes. The mass spectrum of a sample of titanium gave the following data:
Calculate the relative atomic mass of titanium to two decimal places.
(c) State the number of protons, neutrons and electrons in the 4822Ti atom.
Protons:
Neutrons:
Electrons:
(d) (i) State the full electron configuration of the 4822Ti2+ ion.
(ii) Explain why an aluminium-titanium alloy is harder than pure aluminium.
(e) (i) State the type of bonding in potassium chloride which melts at 1043 K.
(ii) A chloride of titanium, TiCl4, melts at 248 K. Suggest why the melting point is so much lower than that of KCl.
(f) TiCl4 reacts with water and the resulting titanium(IV) oxide can be used as a smoke screen.
(i) Formulate an equation for this reaction.
(ii) Suggest one disadvantage of using this smoke in an enclosed space.
3. Vanadium, another transition metal, has a number of different oxidation states.
(a) Determine the oxidation state of vanadium in each of the following species.
V2O5:
VO2+:
(b) Formulate an equation for the reaction between VO2+ (aq) and V2+ (aq) in acidic solution to form V3+ (aq).
2017年5月IB化学SL真题余下省略！
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