Calculate the mass of caustic soda NaOH, which must be taken to prepare a 10% solution weighing 400 g

Calculate the mass of caustic soda NaOH, which must be taken to prepare a 10% solution weighing 400 g with a mass fraction of NaOH of 10%.

The solution consists of two components. Dissolved substance and solvent.

The weight of the solution is 400 grams.

Let’s calculate the weight of the alkali.

To do this, we multiply its mass fraction by the weight of the alkali.

M substance = 400 x 0.1 = 40 grams;

In a similar way, we calculate the weight of the solvent.

M solvent = 400 x 0.9 = 360 grams;

Checking: M substance + M solvent = M solution = 40 + 360 = 400 grams;