Question

How many grams are in 4.02 x 10^21 atoms of calcium?

Answer 1

0.268grams

Explanations:

According to the Avogadro's constant

1 mole of an atom = 6.02 * 10^23 molecules

Given the following

atoms of calcium = 4.02 x 10^21 atoms

Determine the moles of calcium

`\begin{gathered} moles\text{ of Ca}=(4.02*10^(21))/(6.02*10^(23)) \\ moles\text{ of Ca}=0.668*10^(21-23) \\ moles\text{ }of\text{ Ca}=0.668*10^(-2) \\ moles\text{ of Ca}=0.00688moles \end{gathered}`

Determine the mass of Calcium

`\begin{gathered} Mass=mole* molar\text{ mass} \\ Mass=0.00688*40.078 \\ Mass\text{ of Ca}=0.268gram \end{gathered}`

Hence the required grams in 4.02 x 10^21 atoms of calcium is 0.268grams