Neutralization中和作用

1. 其實呢個方法係用黎prepare一些soluble salts, 也就是說一開始obtain到的是solution, 不是直接地得到solid。所以用excess insoluble reactants 就是要肯定所有acid已被neutralized，那剩下的便只是salt solution和insoluble reactants。這時候可以用filtration把insoluble reactants隔開，那便剩下salt solution了；再用crystallization(加熱solution至saturated,然後靜心等候數天至數星期=])就可以得到salt crystal了 (當然是solid的)

2. Silver Chloride, Lead Sulphate, calcium carbonate, magnesium hydroxide...

1. it is to ensure all acid is used up in the reaction. And the product is pure, not contaminated with acid. On the contary, if excess acid is added, the acid cannot be filtered out.

2. any insoluble solid ...