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

1 Answer

Answer:

#"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