2012年5月IB化学SL真题下载-Paper2
1. Propanone reacts with bromine in acidic solution according to the following equation.
A student investigated the kinetics of this reaction using data logging equipment. Her data are shown below.
(a) (i) Identify the reagent the student used to monitor the rate of reaction.
(ii) Calculate the rate of reaction for Experiment 5 and comment on the precision of your result.
(iii) Determine the percentage uncertainty in the calculated rate for Experiment 4.
(b) (i) Describe how the rate of reaction changes when the concentration of CH3COCH3 is doubled and explain this change on a molecular level.
(ii) The student suggested that H+ acts as a catalyst in the reaction. Describe the effect of a catalyst on a chemical reaction.
(iii) Comment on whether or not this hypothesis is supported, with reference to the chemical equation and the experimental data.
2. In 1921 Thomas Midgley discovered that the addition of a lead compound could improve the combustion of hydrocarbons in automobile (car) engines. This was the beginning of the use of leaded gasoline (petrol).
The percentage composition, by mass, of the lead compound used by Midgley is shown below.
(a) (i) Determine the empirical formula of the lead compound.
(ii) Leaded gasoline has been phased out because the lead(IV) oxide, PbO2, produced as a side product in the combustion reaction, may cause brain damage in children.
0.01 mol of Midgley’s lead compound produces 0.01 mol of lead(IV) oxide. Deduce the molecular formula of Midgley’s compound.
(iii) Determine the equation for the complete combustion of Midgley’s compound.
(b) The combustion of unleaded gasoline still produces pollution with both local and global consequences. Identify one exhaust gas which causes local pollution and one exhaust gas which causes global pollution.
Local pollutant:
Global pollutant:
3. Compound X (shown below) is produced by bacteria living in human armpits and is thought to be partly responsible for unpleasant body smells.
(a) Bromine water can be used to test for the presence of one of the functional groups in X. Identify this functional group and describe the colour change observed.
(b) The other functional group changes when X is refl uxed with acidifi ed excess potassium dichromate(VI) to produce a compound Y.
(i) Identify the functional group present in Y but not in X.
(ii) State the type of reaction that X undergoes to form Y.
(c) A different compound is produced if excess X is heated with acidified potassium dichromate(VI) and the product Z is distilled off as it forms.
(i) Identify the functional group present in Z but not in X.
(ii) Predict the order of increasing boiling point of the compounds X, Y and Z and explain your answer.
2012年5月IB化学SL真题余下省略！
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