# How many grams of a 10% solution of hydrofluoric acid can be obtained by dissolving hydrogen

How many grams of a 10% solution of hydrofluoric acid can be obtained by dissolving hydrogen fluoride obtained by the interaction of 117 grams of calcium with sulfuric acid in water?

Given:
ω (HF) = 10%
m (CaF2) = 117 g

To find:
m solution (HF) -?

Solution:
1) CaF2 + H2SO4 => 2HF + CaSO4;
2) M (CaF2) = Mr (CaF2) = Ar (Ca) * N (Ca) + Ar (F) * N (F) = 40 * 1 + 19 * 2 = 78 g / mol;
3) n (CaF2) = m (CaF2) / M (CaF2) = 117/78 = 1.5 mol;
4) n (HF) = n (CaF2) * 2 = 1.5 * 2 = 3 mol;
5) M (HF) = Mr (HF) = Ar (H) * N (H) + Ar (F) * N (F) = 1 * 1 + 19 * 1 = 20 g / mol;
6) m (HF) = n (HF) * M (HF) = 3 * 20 = 60 g;
7) m solution (HF) = m (HF) * 100% / ω (HF) = 60 * 100% / 10% = 600 g.

Answer: The mass of the HF solution is 600 g.

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