Question

Haemoglobin contains $4.6\%$ of iron by mass. If the compound contains a single atom of iron then what is its molar mass in ${gmol}^{-1}$?

• A. $1217.4$
• B. $1324.7$
• C. $1232.4$
• D. $1317.5$

Answer 1

Answer: (A)

The percentage of Iron is $4.6\%$

This means that $4.6g$ of Iron will be present in $100g$ of haemoglobin.

1 g of iron will be present in $\frac{100}{4.6}g$ of haemoglobin.

Molar mass of Iron $56gmo{l}^{-1}$

$56gmo{l}^{-1}$of iron will be present in $\frac{100\times 56}{4.6}gmo{l}^{-1}$ of haemoglobin.

$Molarmassofhaemoglobinis=\frac{5600}{4.6}=1217.4gmo{l}^{-1}$