Calculate the mass of the salt that is formed by the interaction of potassium hydroxide with 300 g

Calculate the mass of the salt that is formed by the interaction of potassium hydroxide with 300 g of a 15% phosphoric acid solution.

Given:

m (H3PO4) = 300 g

w% (H3PO4) = 15%

Find:

m (salt) -?

Solution:

H3PO4 + 3KOH = K3PO4 + 3H2O, – we solve the problem based on the composed reaction equation:

1) Find the mass of phosphoric acid in solution:

m (H3PO4) = 300 g * 0.15 = 45 g

2) Find the amount of phosphoric acid:

n (H3PO4) = m: M = 45 g: 98 g / mol = 0.46 mol

3) We compose a logical expression:

if 1 mol of H3PO4 gives 1 mol of K3PO4,

then 0.46 mol of H3PO4 will give x mol of K3PO4,

then x = 0.46 mol.

4) we find the mass of potassium phosphate formed during the reaction:

m (K3PO4) = n * M = 0.46 mol * 212 g / mol = 97.52 g.

Answer: m (K3PO4) = 97.52 g.