Question

calculate the number of molecules of NO2 present in 138g of NO2 where atomic mass of Nis 14g and O is 16g
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Answer 1

Answer:-

1.8066×10²⁴ molecules

Explanation:-

• Molar mass of Nitrogen (N) = 14g/mol

• Molar mass of Oxygen (O) = 16g/mol

Hence, molar mass of NO₂ :-

= 14 + 16×2

= 14 + 32

= 46 g/mol

Number of mole in 138g of NO₂ :-

= Given Mass/Molar mass

= 138/46

= 3 mole

Hence, 3 moles are there.

Now we know that :-

Number of molecules :-

= No of mole × Avogadro Number

• Avogadro number = 6.022×10²³

= 3×6.022×10²³

= 18.066×10²³

= 1.8066×10²⁴ molecules

Thus, 1.8066×10²⁴ molecules are present in 138g of NO₂ .

Some Extra Information:-

Number of mole :-

(1) Given Mass/Molar mass

(2) No of particles/Avogadro Number

Number of atoms :-

= No of mole × Avogadro Number

Mass :-

= No of mole × Molar mass