A student compares the relative rates of hydrolysis of 1-chlorobutane, 1-bromobutane, and 1-iodobutane by heating each haloalkane with a mixture of ethanol and aqueous silver nitrate.
Which statement correctly explains the chemistry of this investigation?
The rate of precipitate formation increases in the order 1-chlorobutane<1-bromobutane<1-iodobutane\text{1-chlorobutane} < \text{1-bromobutane} < \text{1-iodobutane}1-chlorobutane<1-bromobutane<1-iodobutane because the carbon–chlorine bond has the lowest bond enthalpy.
Ethanol acts as the nucleophile to attack the electron-deficient carbon atom, while water acts as a co-solvent to dissolve the silver nitrate.
Water acts as the nucleophile that hydrolyses the haloalkane, and the relative rate is monitored by measuring the time taken for a silver halide precipitate to form.
Silver nitrate acts as a catalyst that lowers the activation energy of the substitution reaction, leaving the silver ions unchanged at the end of the reaction.
15 exam-style questions on OCR A A Level Chemistry Haloalkanes. Each one has a worked solution and a mark scheme showing where the marks go.