2010 PMR Science Paper 2 (Continuation)

7.  Diagram 7 shows the apparatus set-up to study the fractional distillation of petroleum.

(a) (i) Based on the observation in Diagram 7, record the readings of thermometer in L and N into Table 7.1.

Reading of thermometer	Temperature (oC)
L	36
M	52
N	88

(ii) Compare the colour of the distillate in fraction 2 and fraction 3.

    The colour of the distillate in fraction 2 is lighter than in fraction 3.

(iii) State one hypothesis that can be made from this study.

     The higher the temperature, the darker the colour of the distillate.

(b) State the variables involved in this study.

Manipulated variable	Temperature
Responding variable	Distillate colour

 

(c) Table 7 .2 shows the result of this study.

(i) Based on the result in Table 7 .2, state one inference about the soot produced during the burning of the distillate.

    As the temperature/boiling point increases, more soot is produced because the fraction is less combustible.

(ii) Predict the colour of the distillate if the temperature is more than 200^oC.

     Darker than yellow//dark yellow //brown