Question

find out number of molecules of HNO3 in 630 gram of it
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Answer 1

Answer:-

6.022×10²⁴ molecules

Explanation:-

• Molar mass of Hydrogen (H) = 1g/mol

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

• Molar mass of Oxygen (O) = 16g/mol

Hence, molar mass of HNO₃ :-

= 1 + 14 + 16×3

= 15 + 48

= 63g/mol

Number of moles in 630g of HNO₃ :-

= Given Mass/Molar mass

= 630/63

= 10 moles

∴ 10 moles are present.

• Avogadro Number = 6.022×10²³

Number of molecules :-

= No of moles × Avogadro Number

= 10 × 6.022×10²³

= 60.22×10²³

= 6.022×10²⁴ molecules

Thus, 6.022×10²⁴ molecules are there in

630g of HNO₃ .

Answer 2

We have,

Given mass of nitric acid = 630 g

Molar mass of nitric acid (HNO_3) = 63 g

We know,

Number of molecules = No. of moles × N_A

and, No. of moles = (Given mass)/(Molar mass)

⇒ Number of molecules = (Given mass)/(Molar mass) × N_A

⇒ No. of molecules = (630 g)/(63 g) × 6.022 × 10²³

⇒ No. of molecules = 10 × 6.022 × 10²³

⇒ No. of molecules = 6.022 × 10²⁴ {answer}.