# How many molecules are present in 36.6 L of SO_2 gas at STP?

Approx. $1.66 \times {N}_{A}$ $S {O}_{2}$ molecules, where ${N}_{A} = \text{Avogadro's number, } 6.022 \times {10}^{23}$.
By solving the Ideal Gas equation, we know that at $\text{STP}$ $22.4 \cdot L$ of $\text{Ideal Gas}$ contains $\text{Avogadro's Number} , {N}_{A}$ of molecules.
And thus the number of sulfur dioxide molecules is $\frac{36.6 \cdot L}{22.4 \cdot L} \times {N}_{A}$, whatever this is. Capisce?