Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

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

Draw a diagram to show the apparatus used to carry out electrophoresis. Label each relevant part of the apparatus.

(b)[2]

How far an amino acid travels during electrophoresis is affected by the pH of the solution. For a given potential difference, state two other factors that will determine how far a particular amino acid moves in a fixed time during electrophoresis.

(c)[1]

Many analytical and separation methods depend on substances having different partition coefficients. State what is meant by the term partition coefficient.

(d(i))[4]

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

(d(ii))

The partition coefficient of X between ethoxyethane and water is 40.0. A solution contains $4.00\,\text{g}$ of X dissolved in $0.500\,\text{dm}^3$ of water. Calculate the mass of X that can be extracted from this aqueous solution by shaking it with two successive portions of $0.025\,\text{dm}^3$ of ethoxyethane.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Power supply, buffer, paper/gel and sample all displayed

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI