Question

Calculate the no of atoms present in 20 g of Na2CO3.

Answer 1

1.Molar mass of Na2CO3=106grams
2.Avagardo number=6.022×10^23
3.Given Mass=20 grams
So, the number of atoms =20×6.022×10^23÷106=1.14×10^22 atoms

Answer 2

Given:

Mass of $Na_2CO_3$ = 20g

To find:

No. of atoms present in 20gm of $Na_2CO_3$ = ?

Formula to be used:

Number of moles = $\frac{Given mass}{Molar mass}$

Calculation:

To find number of atoms, moles must be calculated. The formula to calculate number of moles is as follows:

Number of moles = $\frac{Given mass}{Molar mass} = \frac{20}{105}$

Number of moles = 0.1904 moles

1 mole of $Na_2CO_3$ = 6.022 × $10^{23}$

∴ 0.1904 moles of $Na_2CO_3$ = 0.1904× 6.022 ×$10^{23}$ = 1.147×$10^{23}$ atoms.

Conclusion:

Thus it can be inferred that 20g of $Na_2CO_3$ is composed of 1.147×$10^{23}$ atoms.

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