Home › TYS Solutions › O Level Chem › 2019 › P1 Q3

2019 O Level Chem P1 Q3 — Separation Techniques / Distillation and Separating Funnel Solution

Separation Techniques / Distillation and Separating Funnel 2019 O Level Pure Chemistry · Paper 1 · Q3

Question

Liquids X and Y are immiscible. • X has a higher boiling point than Y. • X has a higher density than Y. • X and Y can be separated from each other both by fractional distillation and by use of a separating funnel. Which row correctly gives the first liquid to be collected by fractional distillation and the lower liquid in the separating funnel? Question diagram

Question diagram

Question diagram (continued)

A
B
C
D

Correct answer: C

Video Solution

Explanation

Answer: C (Y collected first by distillation; X is the lower layer in the funnel). Two separate ideas are tested here.

Fractional distillation: the liquid with the lower boiling point boils off and is collected first. The question states X has the higher boiling point, so Y (lower boiling point) is collected first.

Separating funnel: the two liquids are immiscible, so they form layers, and the denser liquid sinks to the bottom. X has the greater density, so X is the lower layer that is run off first.

Putting these together, the first liquid collected by fractional distillation is Y and the lower liquid in the separating funnel is X, which is row C. A common error is to confuse the two properties and assume the denser liquid distils first; in distillation it is boiling point that matters, while in a separating funnel it is density.

Get the Sec 3 / Sec 4 recording package

Every O Level Pure Chemistry TYS MCQ solution video, plus full Sec 3 / Sec 4 topic recordings.