# How many oxygen molecules are needed to make a 3.43*g mass of SO_2?

Sep 12, 2017

Approx. $6.4 \times {10}^{22}$ dioxygens......

#### Explanation:

We need a stoichiometric equation....

$S \left(s\right) + {O}_{2} \left(g\right) \rightarrow S {O}_{2} \left(g\right)$, and I have ASSUMED combustion to give $S {O}_{2}$ ($S {O}_{3}$ is a little trickier!).

And thus there are equimolar quantities of dioxygen and sulfur.

$\text{Moles of sulfur} = \frac{3.43 \cdot g}{32.06 \cdot g \cdot m o {l}^{-} 1} = 0.107 \cdot m o l$.

And thus we need $0.107 \cdot m o l$ dioxygen, and this represents a number of $0.107 \cdot m o l \times 6.022 \times {10}^{23} \cdot m o {l}^{-} 1 = 6.44 \times {10}^{22}$ oxygen MOLECULES.....