# What is the mass in grams of "3.5 moles Ca"?

Nov 9, 2016

#### Answer:

The mass of 3.5 moles of Ca is 140 g to two significant figures.

#### Explanation:

First determine the molar mass of calcium. Molar mass is the mass in grams in one mole of a substance. For elements, we just need the atomic weight on the periodic table written as g/mol.

The molar mass of calcium is 40.078 g/mol.

Now multiply the given number of moles of $\text{Ca}$ by its molar mass.

$3.5 \cancel{\text{mol" "Ca"xx40.078"g"/cancel"mol"="140 g Ca}}$ to two significant figures