A 52-kg woman has 7.2 times 10^-3 mol of hemoglobin (molar mass = 64456 g/mol) in her blood. How many hemoglobin molecules is this?

Answer 1

There are 6.022 x 10²³ molecules per mole (Avogadro's number). As there are 7.2 x 10^-3 moles of hemoglobin, the number of hemoglobin molecules would be 6.022 x 10²³ molecules/mole x 7.2 x 10^-3 moles = 4.3 x 10²¹ molecules.

Answer 2

Hello, Simranjeet,

A mole is defined as 6.02x10²³ of anything: molecules, atoms, paperclips, hot dogs, etc. It is a definition, much like dozen means 12.

The woman has 7x10^-3 moles. To get the actual number of molecules, multiply by the conversion factor, 6.02x10²³ molecules/mole * (7x10^-3 moles). The moles cancel and you are left with molecules of hemoglobin. The molar mass is not needed for this particular question.

Bob

The answer should be around 4.2 x 10²¹ molecules of Hemoglobin, to 2 sig figs.