To 300 g of a 10% glucose solution, 50 g of the substance was added.

To 300 g of a 10% glucose solution, 50 g of the substance was added. Find the mass fraction of the substance in the new solution.

To solve the problem, we use this formula: W = (mr.v – wa / mr – pa) * 100%.
1) It is necessary to calculate the mass of the solute glucose in its solution. To do this, we express the mass of the solute from the formula and get: 300 * 10/100 = 30g.
2) Once we add salt, then both the mass of the solute and the mass of the entire solution change.
3) The mass of the resulting solution: 300 + 50 = 350g.
4) The mass of the solute in the resulting solution: 30 + 50 = 80g.
5) The mass fraction of the substance in the resulting solution is: 80/350 * 100 = 22.9% – the answer.