无水硫酸钠和无水硫酸镁用于干燥的比较/教你如何配碱液
2007-03-11 14:26阅读：
无水硫酸钠干燥能力（程度）较弱，速度慢，优点是吸水量很大，便宜，颗粒大处理方便，属于中性干燥剂,作用慢,因性质稳定和吸水能力强为实验室常用；无水硫酸镁干燥能力略强一点，而速度要快许多，粉末细，属于弱酸性干燥。不与有机物反应.有机物如酯，可用来干燥醛,腈和酰胺。两者属较弱的干燥剂，吸水量甚大，适合于初步干燥。如果要求高的话，需要用更强的干燥剂再深度干燥，强干燥剂一般吸水量小，恰好互补。在实验使用中各自的特点：1．
基本上用Na2SO4
吸水量大，而且吸附的东西较少，过滤颗粒很大，漏的现象很少发生，用MgSO4就很容易漏；2.如果干燥时间比较长，最好选用Na2SO4，因为其吸附能力弱，而MgSO4刚好相反。
对于有机化合物，通常玻璃仪器都用base bath泡，然后水洗，再用de-ionized
water冲。有无机金属离子的玻璃瓶，用王水或者硝酸，硫酸等酸洗液泡，先洗掉无机离子，再在碱桶里泡一阵子之后洗净。这样子，做实验也就不必要为洗玻璃仪器而烦恼。
这里是配base bath的配方，一般玻璃仪器放入base bath之前，要先清理干净，否则容易弄脏了base
bath，导致经常要更换。
http://www.its.caltech.edu/~dmacgrp/guide/BaseBath.pdf
Preparing a base bath
' Put on thick black gloves and eye protection!
' Get a large plastic bucket (~5 gallon)
' Add approximately 200-300g of solid KOH pellets
' Add 4 L of i-PrOH (get reagent grade from VWR stockroom, don't
use HP
LC)
' Carefully add 1L of deionized water
' Leave the bucket in secondary contain (i.e. sink) until KOH is
dissolved and it has
cooled back to room temperature before storing
Always use eye protection and thick black gloves when manipulating
glassware
around the basebath! Rinse gloves after use to prevent spreading
KOH all over your
work area.
Note: base bath will destroy glass fritted funnels and NMR tubes,
H2SO4/H2O2
solutions are frequently used as an alternative for cleaning these
items.
