To interact with 321 g of iron hydroxide 2, 438 g of hydrochloric acid solution was required.

To interact with 321 g of iron hydroxide 2, 438 g of hydrochloric acid solution was required. Determine the mass fraction of hydrochloric acid in this solution.

Decision:

1. Let’s make the equation:

Fe (OH) 2 + 2HCl = FeCl2 + 2H2O;

2. Let’s calculate the molar mass:

M (Fe (OH) 2) = 56 + 16 * 2 + 1 * 2 = 90 g / mol;

3. Find the amount of iron hydroxide:

n (Fe (OH) 2) = m / M = 321: 90 = 3.57 mol;

4. The reaction enters 2 times more acid than hydroxide:

n (HCl) = 2 * 3.57 = 7.14 mol;

5. M (HCl) = 1 + 35.5 = 36.5 g / mol;

6.m (HCl) = n * M = 7.14 * 36.5 = 260.61 g;

7. We calculate the mass fraction:

w (HCl) = (m (HCl): m (HCl solution)) * 100% = (260.61: 438) * 100% = 59.5%

Answer: 59.5%