Which has more number of atoms, 100 grams of sodium or 100 grams of iron (given, atomic mass of Na = 23 u, Fe = 56 u)?
Answer
To find which one has more atoms, we’ll find the number of moles of both.
Since 1 mole of any substance has the same number of atoms, the element having more number of moles will have more atoms .
Let,
Given mass of Na = m n =100g
Given mass of Fe = m f =100g
We know that,
Molar mass of a substance = Atomic mass of the substance (in g)
Therefore,
Molar mass of Na = M n = 23g
Molar mass of Fe = M f = 56g
Now,
Number of moles of a substance = Given mass of the substance / Molar mass of the substance
For Na, = m n /M n
= 100/23
≈ 4.34 moles
For Fe, = m f /M f
= 100/56
≈ 1.78 moles
Since, Number of moles of Na > Number of moles of Fe .
100g of Na will have more atoms than 100g of Fe .
