Answer
Percent impurity = 6.26%
Work Step by Step
1000ml = 1L
21.3ml = 0.0213 L
200ml = 0.200 L
1. Find the volume necessary for an equal number of moles:
$C_1 * V_1 = V_2 * C_2$
$ 0.125* 0.0213= 0.200 * C_2$
$ 0.00266 = 0.200 * C_2$
$C_2 = 0.01331$
2. Find the number of moles:
$Concentration(M) = \frac{n(mol)}{V(L)}$
$0.01331 = \frac{n(mol)}{0.200}$
$0.01331 * 0.200 = n(mol)$
$2.662 \times 10^{-3} moles = n(mol)$
3. Determine the molar mass of this compound $(HC_6H_7O_6)$:
1.01* 1 + 12.01* 6 + 1.01* 7 + 16* 6 = 176.08g/mol
4. Calculate the mass
$mm(g/mol) = \frac{mass(g)}{n(mol)}$
$mm(g/mol) * n(mol) = mass(g)$
$ 176.08 * 2.662 \times 10^{-3} = mass(g)$
$0.4687 = mass(g)$
5. Now, calculate the percent of the mass that reacted:
$\frac{0.4687g}{0.5g} \times 100\% = 93.74\%$
This is the purity; we have to find the impurity:
100% - 93.74% = 6.26%
