Question

Calculate the number of atoms in 120 gram of calcium and 120 gram of iron. Which one has more number of atom and how much will the difference?

Answer 1

Molar mass of Calcium (Ca) = 40 g

We know that the number of atoms in 1 mole of any element is given by the "Avagadro number " which is 6.023 ×10^23 .

So, number of moles in 120 gm of Ca = 120/40

=3

So, number of atoms in 3 moles of Ca = 3 × 6.022×10^23 atoms.

=18.069 ×10^23

Molar mass of Iron (Fe) = 56

Number of moles in Fe = 120/56

=2.14

Number of atoms in 2.14 moles of Fe = 2.14 × 6.023 ×10^23

= 12.89 ×10^23

18.069 × 10^23 > 12.89 ×10^23

So, 120 g of Calcium has more atoms than 120 g of Iron.

Difference = 18.069 ×10^23 - 12.89×10^23

=5.179 ×10^23 atoms.

$\bf{Hope\:it\:helps}$

Answer 2

Answer:calcium had more number of atoms and the difference is 5.179×10^23

Explanation:

Given,

Mass of calcium=120g

Mass of iron=120g

We know,

Molar mass of calcium(ca)=40g

Molar mass of iron(fe)=56g

Avogardo no.=6.022×10^23

So,No. Of atoms in 120 g of calcium

=no. Of moles ×avogardo no.

=given mass÷ molar mass ×avogardo no.

=120÷40×6.022×10^23

=3×6.022×10^23

=18.066×10^23

Again,

No.of atoms in 120 gram of iron

=No. Of moles ×avogardo no.

=given mass÷molar mass×avogardo no.

=120÷56×6.022×10^23

=2.14×6.022×10^23

=12.887×10^23

Therefore,calcium has more no.of atoms

And the

Difference is

18.066×10^23-12.887×10^23

=5.179×10^23

Hope it helps