Question

If I add 25 grams of Fe(OH)2 to 25 ml of water, what is the percent by mass of Iron (II) hydroxide in this solution?

Answer 1

Answer:

50%

Explanation:

Step 1: Calculate the mass of water

Since we don't know the actual temperature at which the solution is prepared, we will assume the density of water is about 1 g/mL.

$25mL \times \frac{1g}{1mL} = 25g$

Step 2: Calculate the mass of the solution

The mass of the solution is the sum of the mass of the solute (Iron (III) hydroxide) and the mass of the solvent (water).

$m(solution) = m(solute) + m(solvent)\\m(solution) = 25 g + 25 g = 50g$

Step 3: Calculate the percent by mass of Iron (III) hydroxide in the solution

$\frac{m(Fe(OH)_3)}{m(solution)} \times 100\% = \frac{25g}{50g} \times 100\% = 50\%$