To a 40% hydrochloric acid solution was added 50 g of pure hydrochloric acid, due to which the concentration

To a 40% hydrochloric acid solution was added 50 g of pure hydrochloric acid, due to which the concentration of such a solution became equal to 60%. Find the initial weight of the solution.

Definition: Percentage is one hundredth of a whole. Percentage is indicated by a% sign. The whole is taken as 100%.

The solution of the problem:

1. Let’s denote the initial weight of the solution by X g. Then it initially contained
X * 40% / 100% = 0.4 * X g of hydrochloric acid.

2. After 50 g of hydrochloric acid was added to the solution, it became (0.4 * X + 50) g ​​of hydrochloric acid.

3. In this case, the concentration of the solution became 60%. That is, we got the equation:
(0.4 * X + 50) / (X + 50) = 60% / 100% = 0.6.

4. Multiply both sides of the equation by (X + 50). We get: 0.4 * X + 50 = 0.6 * X + 30.

5. Let’s perform arithmetic operations. We get: 0.2 * X = 20. Hence X = 100 g.

Answer: the initial weight of the solution is 100 g.