What mass of magnesium contains the same number of atoms as 8.0g of calcium?

1 Answer
Jan 15, 2018

"4.9 g Mg"

Explanation:

Molar Mass of Magnesium ("Mg"): " 24.31 g/mol"
Molar Mass of Calcium ("Ca"): " 40.08 g/mol"

Avogadro's constant = 6.022*10^23 particles of a substance per mol of that substance

8.0"g Ca" * (1 "mol Ca")/(40.08"g Ca")*(6.022*10^23"atoms of Ca")/(1 "mol Ca") = 1.2*10^23"atoms of Ca"

The number of atoms of Mg should be the same as the number of atoms of Ca, so:

1.2*10^23"atoms of Mg"*(1 "mol Mg")/(6.022*10^23"atoms of Mg")*(24.31"g Mg")/(1"mol Mg") = 4.9"g Mg"

You can also eliminate the step of converting to atoms, as a mol of any substance contains 6.022*10^23 particles of that substance