Chemistry 9701 · AS & A Level · Analytical techniques

Analytical techniques — practice question

Electrophoresis is a method that can be used to separate amino acids or peptide fragments in a mixture.
(a)[4]

Draw the apparatus used for electrophoresis, and label every relevant part of the set-up.

(b)[2]

How far an amino acid travels during electrophoresis depends on the pH of the solution. For a given potential difference, state two other factors that influence how far a particular amino acid moves in a fixed time during electrophoresis.

(c)[1]

Several analytical and separation methods depend on substances having different partition coefficients. State what the term partition coefficient means.

(d(i))

The partition coefficient of $X$ between ethoxyethane and water is $40.0$. An aqueous solution contains $4.00\,\text{g}$ of $X$ dissolved in $0.500\,\text{dm}^3$ of water. Calculate the mass of $X$ extracted from this solution after shaking it with $0.050\,\text{dm}^3$ of ethoxyethane.

(d(ii))

Calculate the mass of $X$ extracted from this aqueous solution after shaking it with two separate portions of $0.025\,\text{dm}^3$ of ethoxyethane.

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