2010年第42届IChO预备试题更正1（英文）

Problem 32 Colloid titration titration of a cationic surfactant with polyanion Chemicals benzyldimethyltetradecylammonium chloride Zephiramine Zeph preferably with a concentration ranging from 5 10 5 to 8 10 5 mol L 1 benzyldimethyltetradecylammonium chloride Zephiramine Zeph concentration should be around 1 10 4 mol L 1 0 0025 mol L 1 potassium poly vinylsulfate PVSK titrant 2 5 10 4 mol L 1 potassium poly vinylsulfate PVSK titrant Glassware volumetric pipette 10 mL volumetric pipette 30 mL Procedures 1 Take precisely an aliquot 10 mL of the Zeph sample solution at about 1 0 10 4 mol L 1 and add it to a 200 mL conical beaker using a volumetric pipette then add 1 mL of 0 25 mol L 1 acetic acid and 1 mL of the BCPB solution Check the pH of the solution using pH test paper 1 Take precisely an aliquot 30 mL of the Zeph sample solution and add it to a 200 mL conical beaker using a volumetric pipette then add 1 mL of 0 25 mol L 1 acetic acid and 1 mL of the BCPB solution Check the pH of the solution using pH test paper Problem 36 Hydrolysis of ethyl acetate over a solid acid catalyst Apparatuses and glassware volumetric pipettes 1 mL and 3 mL volumetric pipettes 3 mL and 5 mL Procedure 5 Fill a 25 mL burette with the 0 3 mol L 1 NaOH solution 5 Fill a 25 mL burette with the 0 02 mol L 1 NaOH solution R S Phrases sodium hydroxide 0 3 mol L 1 aq solution 0 02 mol L 1 aq solution Problem 37 Synthesis of a zinc ferrite Procedure 5 Start air bubbling through the glass tube see Fig 1 5 Start air bubbling through the glass tube see Fig 37 1 Problem 39 Synthesis of 1 4 dihydro 2 6 dimethylpyridine 3 5 dicarboxylic acid diethyl ester Hantzsch ester Chemicals toluene hexane