# Chemical analysis shows hemoglobin contains 0.34% of Fe by mass. How many moles of Fe wold be in...

## Question:

Chemical analysis shows hemoglobin contains 0.34% of Fe by mass. How many moles of Fe wold be in a 100.00 g sample?

## Molar Mass:

The molar mass is a useful quantity that helps us prepare solutions for our experiments. We can determine the number of moles in a given amount of mass of a substance by dividing the said mass by the molar mass of the substance. With this, we can accurately prepare solutions of known molarities.

Determine the number of moles of {eq}\displaystyle Fe {/eq}, {eq}\displaystyle n {/eq}, by multiplying the given mass of hemoglobin sample, {eq}\displaystyle m = 100.00 \ g {/eq}, by the mass percentage of {eq}\displaystyle Fe {/eq}, {eq}\displaystyle 0.34\% {/eq}, and then dividing it by the molar mass of {eq}\displaystyle Fe {/eq} (MW = 55.845 g/mol). We proceed with the solution.

{eq}\begin{align} \displaystyle n &= 100.00\ g\times 0.34\%\div 55.845\ g/mol\\ &\approx 0.00608\\ &\approx 6.0\times 10^{-3}\ mol\ Fe \end{align} {/eq}