QUESTION 29 (3 marks)
Methylamine is a weak base that forms a buffer solution when mixed with methylammonium +)(aq). (CH3NH3
a) Describe, using a diagram, the structural formula of methylamine.
[1 mark]
Note: If you make a mistake cancel it by ruling a single diagonal line through your work and use the
QCAA guide · typeset solution
QCAA sample response and mark allocation
29a) | • describes the structural formula for methylamine [1 mark] | |
29b) | Added OH– would react and accept a proton from CH3NH3+ to form water and CH3NH2 (weak base). Thus, equilibrium would shift to the left (reactants) and resist a change in pH. | • explains CH3NH3+ reacts with excess OH– ions [1 mark] • explains equilibrium would shift to the left and resist a change in pH [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
Compare your working with the guide above.