If one molecule of hemoglobin contains 4 iron atoms, and they constitute #0.335%# by mass of hemoglobin, what is the molar mass of hemoglobin?

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Answer 1 · 2016-04-25T10:36:23

#66686.57gmol^-1#, rounded to two decimal places.

Let molecular mass of heamoglobin molecule be #=M#

One molecule of heamoglobin contains #4"Fe"# atoms of atomic mass

#=55.85" each"#,

Total mass of iron in one molecule of heamoglobin

#=4xx55.85=223.4#

To calculate the percentage of iron:

#M# amu of heamoglobin has iron#=223.4#

#100# amu of heamoglobin has iron#=223.4/Mxx100#

Equating to the given value,

#223.4/Mxx100=0.335#

Solving for #M#,

#M=223.4/0.335xx100#

#=66686.57gmol^-1#, rounded to two decimal places.
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At some places the iron percentage in heomoglobin is given as #0.3335%#. Using the published average atomic mass of iron as #55.847#,

#M=66982.9085gmol^-1#