Question

haemoglobin contains 0.25% iron by weight. The molecular weight of haemoglobin is 896000. Calculate the number o iron atom per molecule of haemoglobin. I need a perfect explanation to this question

Answer 1

0.25 % by mass means 0.25 gms of iron in 100 gms of haemoglobin
.therefore in 89600 gms i.e. 1 mole of haemoglobin contains:  0.25 x 89600 = 896 x 0.25 = 224 gms of fe                           
But 1 mole of Fe i.e. 56 gms contains 6.023 x $10^{23}$ ( Avogadro 's number) atoms.

therefore 224 gms of Fe will contain:  224 x 6.023 x$10^{23}$  = 2.409 x 1024 atoms.

you can take NA as 6.022*10^23 also
                                                               56

Answer 2

Answer:

Mass % of Fe in Hb = Mass of one Fe/ Mass of Hb(given) X 100

therefore

, 0.25 = x/89600 X 100

x = 224g.

this is the mass of Fe present in the amount of haemoglobin given to us. Now to find the number of Fe atoms simple divide the mass of obtained Fe by the standard mass of fe which is 56.

therefore, 224/56 = 4 atoms!

there you go !!