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.
Yes, if this cooking oil is mixed with water, it will form a separate layer. This is because oil and water do not mix and are called immiscible liquids, forming a heterogeneous mixture.
When mixed, the oil will form the upper layer and water will form the lower layer. Since the oil has a mass of 910 g per litre, it is lighter than water, which causes it to float on top.
The two layers can be separated using a separating funnel. The mixture is poured into the funnel and left undisturbed until the two separate layers are clearly visible.
To collect the liquids, the stopcock of the separating funnel is opened slowly to drain the lower layer of water carefully into a container. The stopcock is closed when the water is almost fully drained.
Diagram Description: A separating funnel is drawn as an inverted pear-shaped glass vessel with a stopcock at its narrow lower end. Inside the funnel, the top half is labelled 'Oil (Upper Layer)' and the bottom half is labelled 'Water (Lower Layer)'.
Explanation
The question tests the understanding of immiscible liquids and their separation. The context explicitly states that oil and water do not mix, forming separate layers (immiscible liquids). Because the oil weighs 910 g per litre, it is less dense than water, so it forms the upper layer. The context identifies the separating funnel as the apparatus used to separate such mixtures by opening the stopcock to drain the lower layer first.
Solution Steps
Step 1: Identify that oil and water are immiscible liquids that form separate layers.
Step 2: Determine that oil (910 g/L) is lighter than water, so oil forms the upper layer and water forms the lower layer.
Step 3: Pour the mixture into a separating funnel and let it stand undisturbed.
Step 4: Open the stopcock slowly to collect the lower layer of water into a container.
Step 5: Close the stopcock and collect the upper layer of oil separately.