# What is the density of carbon monoxide gas, CO, at STP?

We use the molar volume of an ideal gas at $S T P$ to give ${\rho}_{C O} \cong 1.2 \cdot g \cdot {L}^{-} 1$
At $S T P$, the molar volume of an Ideal Gas $=$ $22.414 \cdot L \cdot m o {l}^{-} 1$.
Now $\rho , \text{density"="Mass"/"Volume}$ $=$ $\frac{28.0 \cdot g}{22.414 \cdot L}$ $=$ ??