# 30%氢氧化钾溶液配置方法简述

The chemical formula of KOH is white powder or flake solid. Its melting point is 380 ℃, and its boiling point is 1324 ℃. It has the characteristics of strong alkali and corrosiveness. When exposed to the air, it is easy to absorb water in the air and deliquesce, and absorb carbon dioxide to form potassium carbonate. Soluble in water, ethanol and glycerin. When dissolved in water, alcohol or treated with acid, a lot of heat will be generated.

The following is the preparation method of 30% potassium hydroxide solution:
1、计算氢氧化钾和水的比例：这里以30%氢氧化钾溶液为例，那么则需要氢氧化钾30g，水80g。
1. Calculate the proportion of potassium hydroxide and water: take 30% potassium hydroxide solution as an example, then 30 g of potassium hydroxide and 80 g of water are needed.
2、称取氢氧化钾和水，可用天平等相关仪器精确称取。
2. Weigh potassium hydroxide and water, and use balance and other relevant instruments to weigh accurately.
3、将氢氧化钾缓慢的倒入水中，用玻璃杯缓慢搅拌，直至均匀。
3. Slowly pour the potassium hydroxide into the water and stir with a glass until it is even.
4、标定：一般先称取定量溶液放入烘箱中烘干至工作基准试剂邻苯二甲酸氢钾，再溶于无二氧化碳的水中，使用酚酞试剂进行标定。临用前标定。
4. Calibration: generally, take a quantitative solution and dry it in the oven to the working reference reagent potassium hydrogen phthalate, then dissolve it in the water without carbon dioxide, and calibrate it with phenolphthalein reagent. Pre use calibration.

The concentration of potassium hydroxide standard titration solution, expressed in moles per liter, is calculated according to the following formula:

Where, m — the accurate value of the mass of potassium hydrogen phthalate, unit: G;
V1–氢氧化钾-乙醇溶液的体积的数值，单位为毫升（ml）；
V1 — volume value of potassium hydroxide ethanol solution, unit: ml;
V2–空白试验氢氧化钾-乙醇溶液的体积的数值，单位为毫升（ml）；
V2 — volume value of potassium hydroxide ethanol solution in blank test, unit: ml;
M–邻苯二甲酸氢钾的摩尔质量的数值，单位为克每摩尔（g/mol）[M(KHC8H4O4)=204.22]
M — value of molar mass of potassium hydrogen phthalate, in g / mol [M (khc8h4o4) = 204.22]