# Question #85ef8

Jan 13, 2017

You first work out the molar mass of potassium sulfide.

#### Explanation:

The molecular formula is ${K}_{2} S$ so we add the atomic masses from the periodic system chart:
$m \left({K}_{2} S\right) = m \left(K\right) + 2 \times m \left(S\right) = 39.10 + 2 \times 32.07 = 103.24$
If we take this in grams, we have one mol (or mole).

So 5.8 mol would be $5.8 \times 103.24 \approx 599 g$

If we take care of the 2 significant digits in the 5.8, AND use the SI-unit, the answer would be $0.60 k g$ In grams it would be $6.0 \times {10}^{2} g$