Question

How many atoms are in 167 g of calcium?

Answer 1

remind that mass=number of moles x molar mass and molar mass of Ca is 40
`167=n*40`
`n=4.175`
1 moles =`6.02 × 10^23`atoms
therefore 4.1752 moles of Ca=`4.175*6.02 × 10^23`=`2.51335× 10^24`atoms

Answer 2

`m=167g`
`M(Ca)=40.078g/(mol)`

Explanation:

`n=m/M=167g/(40.078 g/(mol))=4.167 mol`
`n`-numbers of mol

`N=n*N_a=4.167 mol*6,022 × 10^(23)` (atoms)/(mol)
`=25*10^(23)` atoms

`N_a`- Avogadro's constant`=6,022 × 10^(23)` (atoms)/(mol)