Ethanal (CH3CHO\text{CH}_3\text{CHO}CH3CHO) reacts with the weak acid HCN\text{HCN}HCN to form a hydroxynitrile. This hydroxynitrile is usually prepared by the reaction of ethanal with KCN\text{KCN}KCN followed by dilute acid, instead of using HCN\text{HCN}HCN alone.
State one hazard associated with the use of KCN\text{KCN}KCN.
Suggest a chemical reason, other than safety, why KCN\text{KCN}KCN is used instead of HCN\text{HCN}HCN.
Outline the nucleophilic addition mechanism for the reaction of ethanal with KCN\text{KCN}KCN followed by dilute acid.