Reactions of alkenes and alcohols (chemistry only) common mistakes

Common mistakes

• Confusion Between Carboxylic Acids and Alcohols

  Students often confuse the functional groups of carboxylic acids and alcohols, leading to incorrect descriptions of their reactions.

  Fix itReview the functional groups: carboxylic acids contain –COOH, while alcohols contain –OH. Practice writing the reactions between them to reinforce understanding.

• Weak acid misconception

  Students think carboxylic acids are strong acids because they contain an –OH group, just like alcohols.

  Fix itExplain that the –COOH group can donate a proton, but the resulting –COO⁻ conjugate base is resonance‑stabilised, making the acid weak; contrast with alcohols, which do not ionise appreciably.

• Confusing Carboxylic Acids with Alcohols

  Students often confuse carboxylic acids with alcohols, especially when given names or formulae.

  Fix itRemember that carboxylic acids contain the functional group –COOH, while alcohols contain the –OH functional group. Practice identifying the functional groups in different compounds.

• Confusing Alkenes and Alcohols

  Students often confuse alkenes with alcohols, thinking both can be used to make polymers.

  Fix itRemember that alkenes are hydrocarbons with a double bond and are used in addition polymerisation, while alcohols contain the –OH functional group and do not form addition polymers.

• Misunderstanding Monomers and Polymers

  Students often confuse monomers with polymers, thinking they are the same.

  Fix itRemember that monomers are the small molecules that join together to form large molecules called polymers. Focus on the definition and examples of each.

• Confusing Repeating Units

  Students often think that the repeating unit in addition polymers is different from the monomer, leading to incorrect representations.

  Fix itRemember that in addition polymers, the repeating unit is identical to the monomer since no other molecule is produced during the reaction.

• Identifying Addition Polymers

  Students often confuse addition polymers with condensation polymers, failing to recognize that addition polymers are formed from monomers with C=C functional groups.

  Fix itFocus on the structure of the monomers; remember that addition polymers are made from monomers that contain a carbon-carbon double bond (C=C) and do not lose any small molecules during polymerization.

• Misunderstanding Polymer Formation

  Students often confuse the process of polymer formation from monomers, thinking that the polymer structure is the same as the monomer structure.

  Fix itRemember that in addition polymerisation, the repeating unit in the polymer has the same atoms as the monomer, but the structure is extended to form a long chain.

• Confusing Repeating Units

  Students often confuse the repeating unit of a polymer with the original monomer, thinking they are the same.

  Fix itRemember that the repeating unit is derived from the monomer but may not be identical; it reflects the structure of the monomer without any small molecules lost during polymerisation.

• Confusing Functional Groups

  Students often confuse monomers with one functional group with those that have two functional groups, leading to incorrect identification of condensation polymerisation.

  Fix itRemember that condensation polymerisation specifically requires monomers with two functional groups, which allows them to react and form polymers while releasing small molecules like water.