2013年5月IB化学SL真题下载-Paper2
1. A student decided to determine the molecular mass of a solid monoprotic acid, HA, by titrating a solution of a known mass of the acid.
The following recordings were made.
(a) Calculate the mass of the acid and determine its absolute and percentage uncertainty.
(b) This known mass of acid, HA, was then dissolved in distilled water to form a 100.0 cm3 solution in a volumetric flask. A 25.0 cm3 sample of this solution reacted with 12.1 cm3 of a 0.100 mol dm–3 NaOH solution. Calculate the molar mass of the acid.
(c) The percentage composition of HA is 70.56 % carbon, 23.50 % oxygen and 5.94 % hydrogen. Determine its empirical formula.
(d) A solution of HA is a weak acid. Distinguish between a weak acid and a strong acid.
(e) Describe an experiment, other than measuring the pH, to distinguish HA from a strong acid of the same concentration and describe what would be observed.
2. Table 8 of the Data Booklet shows the atomic and ionic radii of the elements.
(a) Describe and explain the trend in atomic radius across period 3.
(b) A student formulates the following hypothesis: “If phosphorus were to form a positive ion, P3+, its ionic radius would probably be between 110×10–12m and 212 ×10–12m.”Evaluate this hypothesis.
3. Both sodium and sodium chloride can conduct electricity.
(a) Compare how electric current passes through sodium and sodium chloride by completing the table below.
(b) Sodium can be obtained by electrolysis from molten sodium chloride. Describe, using a diagram, the essential components of this electrolytic cell.
(c) State one example that shows the economic importance of electrolysis.
2013年5月IB化学SL真题余下省略！
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