The reaction of iron weighing 8 g with chlorine yielded iron chloride (3), which was dissolved in water

The reaction of iron weighing 8 g with chlorine yielded iron chloride (3), which was dissolved in water weighing 200 g. What is the mass fraction of the salt of the resulting solution?

To solve this problem, we write down the given: m (Fe) = 8 g, m (H2O) = 200 g

Find: mass fraction of salt in solution.

Decision:

Let’s write down the reaction equation.

Fe + Cl2 = FeCl3

Let’s arrange the coefficients.

2Fe + 3Cl2 = 2FeCl3

Let’s calculate the molar masses of iron and iron (III) chloride.

M (Fe) = 56 g / mol

M (FeCl3) = 56 + 35.5 * 3 = 162.5 g / mol

Over the iron we write 8 g, and under the iron – 112 g.

Above iron (III) chloride we write x g, and under iron (III) chloride – 325 g.

Let’s compose and solve the proportion.

x = 8 * 325/112 = 23.2 g

Let’s calculate the mass of the solution.

m (solution) = m (substance) + m (H2O)

m (solution) = 23.2 + 200 = 223.2 g

Let’s write down the formula for finding the mass fraction of a substance and make a calculation.

w = m (substance) / m (solution)

w = 23.2 / 223.2 = 0.104 or 10.4%

Answer: 0.104 or 10.4%