To obtain 95% sulfuric acid, add 100% sulfuric acid to 50 g of 80% sulfuric acid. Find the mass of 100% acid.

Let’s designate the amount of kg of 100% acid for x.

The amount of acid in 50 kg of an 80% solution is 50 * 0.8 (kg).

The amount of acid in x kg of a 100% solution is x * 1 (kg).

The amount of acid in the resulting 95% solution is 0.95 * (50 + x).

Let’s make the equation: 50 * 0.8 + x * 1 = 0.95 * (50 + x).

We solve this equation.

40 + x = 47.5 + 0.95x;

x – 0.95x = 47.5 – 40;

0.05x = 7.5;

x = 150 (kg).

Answer: you need 150 kg of 100% solution.