The Gas Laws

2-minute read
Table of Contents

These laws describe the relationships between the physical quantities pressure, volume and temperature as they relate to gases.

Why Learn the Gas Laws?

  • The gas laws tell us how gases behave when subjected to various pressures ($P$), made to fit into certain volumes ($V$) or kept at specific absolute temperatures ($T$)
  • Very important when combinations of these situations are considered
  • Each law usually keeps one physical quantity constant while varying the others so as to have us see the relationship between those varied quantities

Boyle’s Law

  • Named after physicist and chemist Robert Boyle
  • The pressure of a fixed mass of gas is inversely proportional to its volume at a constant temperature:
$$ \begin{equation}\begin{aligned} P&\propto \frac{1}{V}\\ P&=\frac{k}{V}\ OR\\\ PV&=k\\ \end{aligned}\end{equation} $$

Thus we can have $P_1V_1=k$ and $P_2V_2=k$. Combining these two we get: $$ \begin{equation}\begin{aligned} P_1V_1=P_2V_2\\ \end{aligned}\end{equation} $$ Where $P_1$ is the pressure associated with the gas of volume $V_1$ and $P_2$ is associated with $V_2$.

Example

A small balloon is filled with $0.005\ m^3$ of air and has a pressure of $108\ kPa$.

  • If the balloon is squeezed to cause it to have a lower volume of $0.004\ m^3$, determine the new pressure inside of the balloon.

  • If the balloon can only withstand a pressure of $111\ kPa$, does the balloon pop in the process of squeezing it to this new volume?

Mission details

A gas exerts a pressure of $3\ kPa$ on the walls of container 1. When container 1 is emptied into a $10\ m^3$  container, the pressure exerted by the gas increases to $6\ kPa$. Find the volume of container 1.


Support us via BuyMeACoffee