CAIE A Level Chemistry 9701 · Nitrogen compounds
A mixture contains glycine (), glutamic acid (), and the dipeptide formed from these two amino acids. At pH 7, explain the ionic forms of each species and predict the direction each would move in an electrophoresis experiment. Then explain how the dipeptide's net charge and direction of movement would change if the pH were lowered to 3.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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