190 g of a lithium hydroxide solution was mixed with an excess of potassium phosphate solution.

190 g of a lithium hydroxide solution was mixed with an excess of potassium phosphate solution. Precipitated sediment weighing 34.8 g. Calculate the mass fraction of alkali in the LiOH solution.

The mass of the lithium hydroxide solution is – 190 g.

The sediment weight is 34.8 g.

Let us determine the mass fraction of alkali in the lithium hydroxide solution.

First, you need to write down the reaction equation.

LiOH + K3PO4 = Li3PO4 + KOH.

Determine the molar mass of lithium hydroxide.

M (LiOH) = 24 g / mol.

Molar mass of lithium phosphate.

M (Li3PO4) = 116 g / mol.

Using the reaction equation, we determine the mass of lithium hydroxide.

X g of lithium hydroxide – 34.8 g of lithium phosphate.

24 g / mol – 116 g / mol.

X = 7.2 g of lithium hydroxide.

Determine the molar mass of lithium hydroxide.

W = 7.2 / 190 = 0.038; 3.8%.

Answer: the mass fraction is 3.8%.