Calculate the mass of potassium hydroxide that will be required to prepare a solution weighing 75 g.

Calculate the mass of potassium hydroxide that will be required to prepare a solution weighing 75 g. With a mass fraction of KOH 20%.

The mass of the alkali solution is 75 grams;

To find the mass of alkali, it is necessary to multiply its mass fraction by the mass of the solution.

m of alkali = 75 x 0.2 = 15 grams;

To find the mass of water, it is necessary to subtract the mass of alkali from the mass of the solution:

m of water = 75 – 15 = 60 grams;

The density of water is 1 gram / cm3. To prepare this solution, you need to measure out 60 milliliters of water.

Check: 60 + 15 = 75;