# What is the partial pressure of carbon dioxide?

Mar 24, 2018

In what gaseous mixture? The air we breathe?

#### Explanation:

Well, in $100 \cdot g$ of dry air there are $78.09 \cdot g$ $\text{dinitrogen}$, $20.95 \cdot g$ $\text{dioxygen}$, $0.93 \cdot g$ $\text{argon}$, and $0.04 \cdot g$ $\text{carbon dioxide}$, and small amounts of other gases.

And thus ${\chi}_{C {O}_{2}}$, $\text{the mole fraction of carbon dioxide,}$

$= \frac{\frac{0.04 \cdot g}{44.01 \cdot g \cdot m o {l}^{-} 1}}{\frac{78.09 \cdot g}{28.01 \cdot g \cdot m o {l}^{-} 1} + \frac{20.95 \cdot g}{32.0 \cdot g \cdot m o {l}^{-} 1} + \frac{0.04 \cdot g}{44.01 \cdot g \cdot m o {l}^{-} 1} + \frac{0.93 \cdot g}{39.9 \cdot g \cdot m o {l}^{-} 1}}$

${\chi}_{C {O}_{2}} = 2.62 \times {10}^{-} 4$...and since the pressure is assumed to be $1 \cdot a t m$...${p}_{C {O}_{2}} = 1 \cdot a t m \times {\chi}_{C {O}_{2}} = 2.62 \times {10}^{-} 4 \cdot a t m$..