I did a lab on alkene diastereomers and I'm a bit confused as to what the purpose was. We reacted maleic acid with a temporary carbocation to see whether the product would be maleic acid or fumaric acid. These are alkene diastereomers of each other. My results suggested that the product was maleic acid. I don't quite understand the theory... the pre-lab question said: "Will one of the alkene diastereomers be formed preferentially from the carbocation? If so, which one is favoured?" ... Can anyone tell me what this means?