银氨溶液的制备：NH3·H2O + AgNO3 == AgOH + NH4NO3 ,AgOH + NH3·H2O == Ag(NH3)2OH + H2O
操作：往硝酸银溶液中逐滴加入氨水,直至最初产生的沉淀恰好完全溶解为止!
乙醛银镜反应：CH3CHO + Ag(NH3)2OH =水浴加热= NH4COOH + H2O + Ag↓ + 3NH3