# A certain protein was found to contain 0.129% iron by mass. Determine the minimum molecular mass...

## Question:

A certain protein was found to contain 0.129% iron by mass. Determine the minimum molecular mass of the protein.

## Molar Mass

The bulk property of any substance can be defined by the molar mass of that particular substance. It is usually determined in atomic mass units and can be calculated with the help of moles and the given mass of the substance.

Given Data:

• The percentage of iron (by mass) in the protein is 0.129 %

The protein contains 0.129% iron by mass means that 0.129 g of iron is present in 100 g of protein.

The molar mass of iron is 55.845 g/mol.

The number of moles of iron present in 100 g of protein can be calculated as shown below.

{eq}\begin{align*} {\rm{Moles}} &= \dfrac{{{\rm{Given}}\;{\rm{Mass}}\left( {\rm{g}} \right)}}{{{\rm{Molecular}}\;{\rm{Mass}}\left( {{\rm{g/mol}}} \right)}}\\ &= \dfrac{{0.129\;{\rm{g}}}}{{55.845\;{\rm{g/mol}}}}\\ &= 0.00231\;{\rm{mol}} \end{align*} {/eq}

Therefore, the minimum molecular mass of protein can be calculated as shown below.

{eq}\begin{align*} {\rm{Minimum}}\;{\rm{molecular}}\;{\rm{mass}}\;{\rm{of}}\;{\rm{protein}} &= \dfrac{{{\rm{Mass}}\;{\rm{of}}\;{\rm{protein}}\left( {\rm{g}} \right)}}{{{\rm{Moles}}\;{\rm{of}}\;{\rm{Iron}}}}\\ &= \dfrac{{100\;{\rm{g}}}}{{0.00231\;{\rm{mol}}}}\\ &= 43290.04{\rm{g/mol}} \end{align*} {/eq}

The minimum molecular mass of protein is {eq}\boxed{{\rm{43290.04}\;{\rm{g/mol}}}} {/eq} 