# A student collects 450 mL of HCl (g) at a pressure of 100 kPa and a temperature of 17°C. What is the new volume of the HCl at standard temperature and pressure?

Mar 28, 2016

Take ${V}_{1} / {T}_{1} = {V}_{2} / {T}_{2}$ and rearrange to:

${V}_{2} = \frac{{V}_{1} {T}_{2}}{T} _ 1 = \frac{0.450 \times 273}{290} = 0.424$ $L$ = $424$ $m L$.

#### Explanation:

First convert the temperature to kelvin: $17 + 273 = 290$ $K$. Standard temperature is $273$ $K$.

Now $100$ $k P a$ is already standard pressure, so the pressure is constant.

We should work in SI units, so $450$ $m L$ = $0.450$ $L$.

From the Combined Gas Law, but with pressure omitted because it is constant, take ${V}_{1} / {T}_{1} = {V}_{2} / {T}_{2}$ and rearrange to ${V}_{2} = \frac{{V}_{1} {T}_{2}}{T} _ 1 = \frac{0.450 \times 273}{290} = 0.424$ $L$ = $424$ $m L$.