What mass of salt should be dissolved in 500 g of its 10% solution to increase the mass fraction of salt by 3 times?

1. With an increase of three times, the mass fraction will be:

w2 (salts) = w1 (salts) * 3 = 0.1 * 3 = 0.3;

2.Calculate the initial salt mass:

m1 (salt) = w1 (salt) * m1 (solution) = 0.1 * 500 = 50 g;

3. let x g of salt be added, find the total mass of salt and the mass of the resulting solution:

m2 (salts) = m1 (salts) + x = 50 + x;

m2 (solution) = m1 (solution) + x = 500 + x;

4.express x:

w2 (salt) = m2 (salt): m2 (solution);

0.3 = (50 + x): (500 + x);

150 + 0.3x = 50 + x;

100 = 0.7x;

x = 142.86 g.

Answer: 1) 31.82%; 2) 142.86 g.