Question

How many atoms are in 163 g of calcium?

Answer 1

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles.

163 g Ca (1 mol / 40.08 g) ( 6.022 x 10^23 atoms / 1 mol ) = 2.45 x10^24 atoms Ca

Answer 2

Answer: $24.5\times 10^{23}atoms$

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar Mass}}=\frac{163g}{40g/mol}=4.075moles$

1 mole of calcium contains = $6.023\times 10^{23}atoms$

Thus 4.075 moles of calcium contains = $\frac{6.023\times 10^{23}}{1}\times 4.075 =24.5\times 10^{23}atoms$

Thus there are $24.5\times 10^{23}atoms$ in 163 g of calcium.