How to make 4 molar kcl

Preparation of a KCl solution (potassium chloride)

A 3 molar KCl solution is usually required for the reference electrode. KCl is a salt that easily dissolves in water. Molarity is the concentration of a solution, in this case the amount of KCl in water.

If you want to prepare a 3-molar KCl solution, you can proceed as follows:

The molecular weight of KCl is 74.6 (made up of K = 39.1 and Cl = 35.5). 74.6 g KCl is also called 1 mol, 3 mol is then 223.8 g KCl. This amount is weighed (no high demands are made on the weighing accuracy) and poured into a clean measuring beaker. Make up to one liter with osmosis or deionised water. When the salt has dissolved, the 3 molar KCl solution is ready for use. For the small amounts that are needed to fill up the electrode, it is better to only make up about 1/4 liter of solution. In this case, only 1/4 of the amount of salt, i.e. 56 g of KCl rounded off, should be used.

You can have KCl weighed out by the pharmacist when you buy it, or you can use a scale like the one I built for myself.