Paper Chromatography and Separating immiscible liquids E. Haniff

Objectives Separate a mixture of different solutions using a given solvent (by difference of solubilities) Separate a mixture of immiscible liquids

What are immiscible liquids? Immiscible liquids are two liquids which cannot be dissolved in one another They form two distinct layers

Separating immiscible liquids

Title: Separation of two immiscible liquids Aim: To separate a mixture of oil and water Apparatus and materials: Separating funnel with tap, water, oil and 3 containers

Diagram:

Method The apparatus was set up as shown in the diagram The denser liquid at the bottom of the separating funnel was withdrawn through the tap and collected in a container The container was then replaced with another and a small quantity of liquid was withdrawn (a mixture of the two right after the denser liquid was withdrawn

Method continued… The container was then replaced again and the less dense liquid was allowed to run out and was collected. Observations were noted

Observations Two separate layers were formed in the separating funnel. The oil was seen at the top layer and the water at the bottom layer

Discussion The separation of two immiscible liquids is based on the principle that the two liquids do not mix and form two distinct layers The less dense liquid was the oil, which formed the top layer The denser liquid was the water which formed the bottom layer and was withdrawn first, allowing the separation of the two liquids

Conclusion The mixture of oil and water was separated using a separating funnel Oil and water are immiscible liquids because they do not dissolve one another

Application…. The principle of immiscibility of liquids in some solvents is used in solvent extraction Solvent extraction is used to separate a component from a mixture by using two solvents. Two conditions have to be met: The component must be more soluble in one solvent than in the other The two solvents must be immiscible

For example…pg 75 To compare the solubility of iodine in two solvents Iodine is dissolved in water The water is mixed with 1,1,1-trichloroethane The iodine goes into this solvent and the water can be drained off in a separating funnel

Another example

Uses of solvent extraction Good for removing organic molecules from water For example caffeine from tea or coffee. Caffeine is an organic compound which is more soluble in an organic solvent which is immiscible with water.(Dichloromethane)

Title: Paper Chromatography Aim: To separate the components of screened methyl orange Apparatus and materials: filter paper, beaker, capillary tube, test tube, screened methyl orange

Diagram:

Method: To a strip of filter paper, a capillary tube was used to place a small drop of methyl orange, close to the base of the paper A small volume of water was placed in a test tube or beaker The strip of filter paper was suspended so that it barely touched the solvent

Method: It was left to stand for a while Observations were recorded

Observations The liquid moved up the filter paper Distinct colours could be seen The colour that moved the furthest up the filter paper was…….

Observations

Discussion Chromatography is a technique that uses a stationary phase and a mobile phase The stationary phase is the filter paper in paper chromatography The mobile phase is the solvent that moves up the paper Chromatography can be used to separate minute quantities of substances.

Discussion Separation of the different components occurs because each substance is soluble to different extents in the chosen solvent (the mobile phase) The more soluble component travels the furthest up the filter paper and the least soluble remains closer to the base Two colours were seen in screened methyl orange: two dyes a blue and a yellow

Conclusion Screened methyl orange contains two components: a blue dye and a yellow dye The more soluble component appeared blue in colour The blue dye was more soluble in water

Applications of chromatography Testing for trace contaminants in the environment Monitoring water quality and air quality Analyzing pure samples for trace contaminants (pharmaceutical industry) Quality control in food industry