Answer:
0.2659 moles, to 4 sig figs
Explanation:
The question asks us to convert 14.85g of iron, Fe, into moles of Fe. The molar mass of iron is given as 55.85 g Fe = 1 mole. This is also the atomic weight of iron (element 26). The atomic weights of all the elements are expressed as AMU (atomic mass units), But one magic attribute of the periodic table is that the atomic mass is also the mass of that element that is needed to make one mole, or Avagadro's number of particles (in this cases atoms), or 6.02 x 10^23 toms.
Express this relationship as a conversion factor: (55.85 g Fe)/( 1 mole)
The mass of an iron sample (in grams) can be converted into the number of atoms (in moles) using this factor:
(14.85 g Fe)/[(55.85 g Fe)/( 1 mole)]
Cancel g Fe and move moles to the top:
14.85/(55.85) moles
= 0.2659 moles, to 4 sig figs
