Calculate the mass of 20% hydrochloric acid, which will be required

| September 16, 2021 | education

Calculate the mass of 20% hydrochloric acid, which will be required to remove rust from an iron plate weighing 21.4 g (Note that rust consists only of iron hydroxide (lll).)

1. Let’s write down the equality of chemical interaction:

Fe (OH) 3 + 3HCl = FeCl3 + 3H2O.

2. Find the number of moles of iron hydroxide:

n (Fe (OH) 3) = m (Fe (OH) 3) / M (Fe (OH) 3) = 21.4 g / 107 g / mol = 0.2 mol.

3. Based on the equality of the chemical interaction, we find the number of moles and, as a result, the mass of hydrochloric acid:

n (HCl) = n (Fe (OH) 3) * 3 = 0.2 mol * 3 = 0.6 mol.

m (HCl) = n (HCl) * M (HCl) = 0.6 mol * 36.5 g / mol = 21.9 g.

4. Calculate the mass of the hydrochloric acid solution:

m (solution) = m (HCl) * 100% / ω (HCl) = 21.9 g * 100% / 20% = 109.5 g.

Result: m (solution) = 109.5 g.



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