Question

a) Calculate the number of atoms in 120g of Calcium and 120g of on. Which one has more number of atoms and how much is the difference? (atomic mass of ca = 40u. Fe = 56u) pls answer in steps​

Answer 1

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 atoms in 3 moles of

Ca = 3 × 6.022×10^23 atoms. So, 120 g of Calcium has more atoms than 120 g of Iron. =5.179 ×10^23 atoms

Answer 2

Correct question:-

Calculate the number of atoms in 120g of Calcium and 120g of Iron. Which one has more number of atoms and how much is the difference??

Answer:-

120g of Calcium has more number of atoms. Difference is 0.5189 atoms .

Explanation:-

For 120g of Calcium :-

∵ Atomic mass of calcium is 40u.

∴ Molar mass of calcium is 40g/mol.

Number of moles :-

= Given Mass/Molar mass

= 120/40

= 3 moles

Number of atoms :-

= No of moles × Avogadro Number

= 3×6.022×10²³

= 18.066×10²³

= 1.8066×10²⁴ atoms

For 120g Iron :-

∵ Atomic mass of Iron is 56u.

∴ Molar mass of Iron is 56g/mol.

Number of moles :-

= Given Mass/Molar mass

= 120/56

= 2.14 mole

Number of atoms:-

= No of mole × Avogadro Number

= 2.14×6.022×10²³

= 12.887×10²³

= 1.2877×10²⁴ atoms

Difference in the number of atoms :-

= 1.8066×10²³ - 1.2877×10²³

= 1.8066 - 1.2877

= 0.5189 atoms