Answers section
Questions 2.7 
- State two properties this method of separation relies on ----------------
- Explain why the mouth of separating funnel is plugged with cotton wool. ----
- What would be the problem of decanting off the top oil layer? -------------------
- The boundary mixture consists of small amounts of both components. How can they be separated? ----------------------------------------------------
- Write the procedure for this method of separation. --------------------l
- Name at least three other examples of immiscible liquid-liquid mixtures. ---
NB: Immiscible liquids are best separated using separating funnel.
Answers to Questions 2.7 
- The liquids do not dissolve in each other (Immiscible). They have different densities.
- To minimize the escape (diffusion) of kerosene vapour which causes cancer (is carcinogenic).
- Being denser, water, tends to flow out together with kerosene or any less dense layer at the top.
- By sucking with a dropper
- With the set-up shown, open the tap till nearly all the water flows out into the beaker. Replace the beaker and open the tap to collect the boundary mixture (containing a small amounts of water and kerosene) and close the tap. Place the third beaker and open the tap till all the kerosene flows out into it. Tilt the beaker containing the boundary mixture or transfer it into a test tube then sack out the top kerosene layer using a dropper and transfer it into the beaker containing kerosene.
- Water and cooking oil, water and benzene, water and diesel or petrol, (water and any oil).