An example of the constancy of pressure and volume within a closed system; fixed temperature ensures that energy transfer remains the same, but lessened volume increases the likelihood of collisions.

Boyle's Law and Gay-Lussac's Law are much more accessible if you think about them in terms of fundamental mechanical principles in play at the molecular level. For example, Boyle's Law describes how the pressure changes with the volume of an ideal gas at constant temperature. At its heart, Boyle's Law is telling you how pressure increases with an increase in gas density. Imagine the gas at the point of view of the particles. At greater density, even though the particles are not moving more vigorously (the temperature is constant), there are more particles colliding on a given area. At constant temperature, the pressure goes up as the volume goes down in inverse proportionality.

Gay-Lussac's Law, on the other hand, describes how pressure increases with temperature in a constant volume. Even though the particle density is the same (the volume is the same), because the particles are moving faster at higher temperature, the collisions, which give rise to pressure, must be more vigorous. At constant volume, the pressure is directly proportional to temperature.

The WikiPremed MCAT Course is a comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum. Please read our policies on Privacy and Shipping & Returns.  Contact Us. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course. WikiPremed offers the customers of our publications or our teaching services no guarantees regarding eventual performance on the MCAT.

Creative Commons License
WikiPremed is a trademark of Wisebridge Learning Systems LLC. The work of WikiPremed is published under a Creative Commons Attribution NonCommercial ShareAlike License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions.