Separating a mixture of Oil and Water

Separating a mixture of Oil and Water using a Separating Funnel

Aim / Objective:

To separate a mixture of cooking oil and water.

Abstract:

In this experiment, an immiscible mixture of oil and water was separated using a separating funnel.

Materials/ Apparatus:

measuring cylinder, retort stand, beaker, clamp, separating funnel, conical flask, cooking oil and water,

Method / Procedure:

  1. Use a measuring cylinder to measure 10cm3 of cooking oil and pour it into the conical flask.
  2. Use another measuring cylinder to measure 10cm3 of water and add to the conical flask with the oil.
  3. Mix both liquids by shaking the flask vigorously.
  4. Use a clamp to attach the separating funnel to a retort stand. Ensure that the separating funnel is in the closed position and pour in the mixture of oil and water.
  5. Allow the mixture to settle for a few minutes. Place a beaker under the mouth of the separating funnel and allow the mixture of water to run off in the beaker slowly.
  6. Collect the remaining portions of water and oil and then the pure oil.
Diagram of apparatus showing the separation of a mixture of oil and water using a separating funnel

Diagram of apparatus showing the separation of a mixture of oil and water using a separating funnel

Suggested Results:

When the water was added to the cooking oil, it was seen to be the more dense liquid hence the water settled on top of it. Also in between the layer of pure oil and the layer of pure water, there was a layer consisting of a mixture of oil.

Discussion:

1.What type of mixture is the separating funnel generally used to separate?

>>>The separating funnel is generally used to separate a mixture of immiscible liquids. Immiscible meaning that the liquids do not mix but separate into distinct layers

2. Explain why this technique was suitable in separating the oil from the water.

>>>This technique was ideal for the experiment for when water is mixed with oil, it is known to be immiscible. It forms a total of three layers, a layer of pure oil, pure water and a layer of both water and oil mixed together.

3. Explain the chemical principle underlying the type of mixture formed by oil and water

>>>Pure oil doesn’t mix with water because water is polar solvent and oil is non-polar and like dissolves like. But in between the layer of pure oil and pure water there was a layer of both oil and water. This type of technique can be said to be an emulsion.

4.To what position should the top of the funnel be turned when opening it?

>>>The top should be vertical to allow the water to run out and must be closed before the oil reaches the bottom of the funnel

5.Can separating funnel be used to separate a mixture of ethanol and water? Explain your answer

>>>No. A separating funnel cannot be used to separate ethanol and water because ethanol will dissolve in the water due to polarity hence being classified as miscible liquids. So in order to separate a mixture of ethanol and water, one would have to use fractional distillation.

Source of Error/ Limitations/ Assumptions: 

Р Improper technique of decanting, thus allowing for the layers that were collected to be not entirely pure.

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