Find the mass in grams of 0.75 moles of magnesium (Mg).

Explanation:

We are asked to find the mass of 0.75 moles of magnesium.

Moles are converted to grams using the molar mass. This is the number of grams in 1 mole of a substance. The values are found on the Periodic Table because they are equal to the atomic masses, but the units are grams per mole instead of atomic mass units.

Look up the molar mass of magnesium.

We convert using dimensional analysis. Set up a conversion factor using the molar mass.

We are converting 0.75 moles of magnesium to grams, so we multiply the conversion factor by this value.

The units of moles of magnesium cancel.

0.75 moles of magnesium contains 18.22875 grams of magnesium.