# Hydrogen gas in 500cm^3 container at a pressure of 700 torr is transferred to a container of volume 700 cm^3. What will the new pressure be? a) if no temperature change occurs. b) if it's temperature changes from 25C to 35C?

Apr 23, 2017

Well, the combined gas law holds that $\frac{{P}_{1} {V}_{1}}{T} _ 1 = \frac{{P}_{2} {V}_{2}}{T} _ 2$, so..................

#### Explanation:

So we solve for ${P}_{2}$, and thus ${P}_{2} = \frac{{P}_{1} {V}_{1}}{T} _ 1 \times {T}_{2} / {V}_{2}$, which clearly has the required units of pressure; why?

P_2=(500*cancel(cm^3)xx700*"Torr")/(700*cancel(cm^3))=500*"Torr"

The beauty of using these gas laws, is that (excluding temperature) given the proportionality, we can use whatever outlandish units we want, i.e. ${\text{pounds per square inch, pints, furlongs}}^{3}$.

And for part (b), we must use units of $\text{absolute temperature}$, T_1=298*K; T_2=308*K:

${P}_{2} = \frac{700 \cdot \text{Torr} \cdot 500 \cdot c {m}^{3}}{298 \cdot K} \times \frac{308 \cdot K}{700 \cdot c {m}^{3}}$,

$= 517 \cdot \text{mm Hg}$

What are these pressure in $\text{atmospheres}$?