Drawing and naming the alcohols
3 marks · NormalExplain why both 'propanol' and 'propan-2-ol' could be correct names for different alcohol compounds. Use the structure and position of the –OH group in your answer.
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Must show: Mentions that 'propanol' refers to a 3-carbon alcohol (not specifying position), Explains that 'propan-1-ol' and 'propan-2-ol' differ by the position of the –OH group, States that the number specifies the carbon atom to which –OH is attached
Also accept: Mentions structural isomers
Common mistakes: Not mentioning the significance of the position number; Not explaining what 'propanol' means
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Marking points
M1 · 1 mark · States that 'propanol' refers to 3-carbon chain alcohols generally, or as an acceptable alternate name.
M1 · 1 mark · Explains that 'propan-1-ol' and 'propan-2-ol' differ by the carbon to which –OH attaches.
A1 · 1 mark · Clearly states the number indicates position (carbon 1 or 2), affecting the structure/property.
Worked solution
'Propanol' refers to any alcohol with three carbon atoms. However, the –OH group can be attached to either the first carbon (propan-1-ol) or the second carbon (propan-2-ol). These are isomers because they have the same formula but different structures. Naming with a number ('propan-1-ol', 'propan-2-ol') specifies exactly which carbon has the –OH group.