Recapitulation: Chapter4 23 Q28, 30,32;
Suggestion answer: Question30
b) A=fuel oil, B=gas oil, C=kerosene, D=refinery gas;
c) Check up answer from the table on P13; viscosity increase because the intermolecular forces increases which in fact following the trend of molecular mass.
Sootiness of flame is dependent on the volatility and the hydrogen to carbon ratio of the hydrogen carbon, high H: C ratio gives clean flame or otherwise give sooty flame.
Smell of the fractions is different, the high boiling point fractions are mainly aromatic compounds characterized with stringent smell.
Misconceptions: Question31 and 32
The thermometer bulb should be positioned as one end of the deliver tube.
The deliver tube and the thermometer should be fixed in a 2-holed rubber stopper. (as stated in the question).
Don’t draw too detail about the set up, e.g. matches, Bunsen burner, could be omitted;
Position the apparatus properly; the test tube for collection should only be inclined within 30o.
Don’t describe the “already known experiment steps” e.g. light the Bunsen burner with match...ECT.
Fraction of 40℃ boiling point could not be collected with water bath.
Describe the principle of distillation: “The fraction of low boiling point comes out first. As the fraction is distilled off, the temperature rise up to a higher steady point, change the test tube to collect the next fraction. Repeat the procedure until the highest boiling point fraction is collected.