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Question
The label on a cooking oil pack says one litre (910 g). If this oil is mixed with water, will it form a separate layer? If so, which substance will be on top? How will you separate the two layers? Also, draw the diagram of the apparatus used.
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Answer
Yes, a separate layer forms. The
oil stays on top
, and the two are separated with a
separating funnel
.
Explanation
Oil and water are immiscible , so they never mix. Which one floats is decided by density.
Density of oil
=
mass
volume
=
910 g
1000 mL
=
0.91 g/mL
Density of water
=
1.00 g/mL
0.91 is less than 1.00, so the oil floats and the water settles below.
Method
Use a separating funnel, exactly as in Activity 5.6 — let the two layers form, open the stopcock and run the lower water layer off, then close it and collect the oil separately.
The diagram is the one in Fig. 5.16 — a separating funnel on a laboratory stand, glass stopper on top, oil labelled on the upper layer, water on the lower, stopcock and conical flask below.
← Back to: 5.4.1 Separation of two immiscible liquids
