A plant extract can be obtained with organic solvents such as acetone or ethyl alcohol, and is composed of plant pigments such as chlorophyll A and B, carotene, and xanthophylls. Write a brief explanation about why a plant extract is a mixture, whether it is homogeneous or heterogeneous, and how it can be separated.

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Chemistry

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20 February, 05:00

A plant extract can be obtained with organic solvents such as acetone or ethyl alcohol, and is composed of plant pigments such as chlorophyll A and B, carotene, and xanthophylls. Write a brief explanation about why a plant extract is a mixture, whether it is homogeneous or heterogeneous, and how it can be separated.

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Honey Pie · Answer 1

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Explanation:

A plant extract is a mixture because it contains different substances: acetone or ethanol, chlorophylls A and B, carotene and xanthophylls.

It is homogeneous because it is a solution. There is only one phase: the liquid phase. You cannot see the pigments as separate phases.

You can separate the pigments by paper, thin layer, or column chromatography.

Many schools use paper chromatography, because paper is cheap.

As the mixture of pigments follows the solvent up the paper, they separate into different coloured bands according to their attractive forces to the cellulose in the paper.

The chlorophylls are strongly attracted to the paper, so they don't travel very far.

The nonpolar carotene molecules have little attraction to the polar cellulose, so they are carried along by the solvent front.