Question

calculate the number of moles and number of molecules present in 1.89 g of nitric acid​

Answer 1

Nitric acid formula = HNO3

Mass of Nitric acid = 1 + 14 + 16 x 3 Amu = 63 Amu

$moles \: = \frac{given \: mass}{molecular \: mass} \\ \frac{1.89g}{63amu} = 0.03 \: moles \\ number \: of \: molecules \: = moles \: \times \: avogadro \: number \\ 0.03 \times 6.023 \times 10 {}^{23} = 0.18069 \times 10 {}^{23} \\ 1.8069 \times 10 {}^{22} molecules$

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Answer 2

Given:

The chemical = Nitric Acid

Its composition = 1.89g

To Find:

Number of Molecules

Solution:

Calculating the mass of Nitric acid

= 1 + 14 + 16 × 3

= 15 + 48

= 63 Amu

Moles = Given mass/Molecular Mass

= 1.89/63

= 0.03 moles

Number of molecules = Total moles × Avogadro Number

= 0.03 × 6.023 × 10^23

= 0.18069 × 10^23

= 1.8069 × 10^22

Answer: Number of Molecules is 1.8069 × 10^22