Homework Help

Hemoglobin, the oxygen carrying protein in red blood cells, has four iron atoms per...

user profile pic

spock3 | Student, Undergraduate | (Level 2) Honors

Posted June 27, 2012 at 1:36 PM via web

dislike 0 like

Hemoglobin, the oxygen carrying protein in red blood cells, has four iron atoms per molecule and contains 0.340 percent iron by mass. Calculate...

...the molar mass of hemoglobin.

Show complete step by step solution to explain the process and answer.

3 Answers | Add Yours

user profile pic

etotheeyepi | Student, Undergraduate | (Level 1) Valedictorian

Posted June 28, 2012 at 4:49 AM (Answer #1)

dislike 0 like

The atomic mass of iron, according to the periodic chart, is 55.8g/mole.

Four atoms of iron is 223g/mole

223 = .34 x

x = 223/.34 = 656 g/mole

user profile pic

etotheeyepi | Student, Undergraduate | (Level 1) Valedictorian

Posted June 28, 2012 at 5:34 AM (Answer #2)

dislike 0 like

I forgot to convert 0.34% to a decimal. The equation should be:

223 = .0034 x

so

x = 65,600 g/mole

user profile pic

chaobas | College Teacher | (Level 1) Valedictorian

Posted July 3, 2012 at 2:51 AM (Answer #3)

dislike 0 like

0.340 percent iron by mass means in 100g of haemoglobin there are 0.340 g of irons. and the molar mass of iron is 55.85 g/mol

and we know that there are 4 iron mole in a molecule of haemoglobin, so 

(4 mol Fe/1 mol haemoglobin) * (55.85 g fe/ 1mol Fe)*(100 g of haemoglobin/0.340 g of Fe)

65705.88 g/mol 

so the molar mass of haemoglobin is 65705.88 g/mol or 6.6*10^4 g/mol

 

now haemoglobin is a protein and the molar mass of protein is express in dalton (1 dalton = 1g/mol)

so the molar mass is 6.6*10^4 dalton.

 

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes