# How many grams are there in 5.0 moles of H_2O?

Jan 26, 2017

$90 g$

#### Explanation:

We first determine the molar mass of ${H}_{2} O$ bij adding the atomic masses:
$2 \times 1.008 + 1 \times 16.00 = 18.016 g / m o l$

Multiply by the number of mols:

$5.0 \cancel{m o l} \times 18.016 \frac{g}{\cancel{m o l}} = 90.080 g \approx 90 g$

(we have to round to two significant digits).

Jan 27, 2017

The formula for calculating moles = $\text{mass"/"molar mass}$
Therefore = $\text{ molar mass * moles} = m a s s$

#### Explanation:

molar mass of water = 18g/mol
moles of water = 5
$5 \text{*} 18 = 90$
Therefore there are 90 grams of water