# A gas with a volume of 4.0 L at a pressure of 205 kPa is allowed to expand to a volume of 12.0 L. What is the pressure in the container if the temperature remains constant?

Apr 1, 2017

We use old $\text{Boyle's Law}$, $P V = k ,$ where $k$ is a $\text{constant}$.

#### Explanation:

And the utility of this law means that we could use non-standard units, if our units are consistent.

Given that $P V = k ,$ (temperature constant), it follows that...........

${P}_{1} {V}_{1} = {P}_{2} {V}_{2}$..........

We solve for ${P}_{2} = \frac{{P}_{1} {V}_{1}}{{V}_{2}} = \frac{205 \cdot k P a \times 4.0 \cdot \cancel{L}}{12.0 \cdot \cancel{L}}$

$\cong 68 \cdot k P a$

The pressure has reasonably decreased............Why $\text{reasonably?}$ And given consistent units, I could use $\text{pints}$, $\text{foot lbs}$, $\text{atmospheres}$ whatever...........