Gas Laws

Relationships Between Variables

Avogadro’s Law

Gas Laws

Relationships Between Variables

Learning Target 3.2.2: I can explain the relationships between volume of a gas, its temperature and its pressure using Boyle’s Law, Charles’s Law, Gay-Lussac’s Law, and the Combined Gas Law and how changing one variable affects the others.

Avogadro’s Law

Goal 3.2.2.h I can calculate the change in volume or number of moles of a gas in a closed system if I know the change in volume or number of moles at a constant temperature and pressure using V1/n1 = V2/n2 (Avogadro’s Law)

When you take a deep breath, you inhale a lot of particles of air and the volume of your lungs expands. In Unit 2, you learned that Avogadro’s Law says that no matter what gas you have, an equal number of particles will have the same volume if the pressure and temperature stay the same. This fits with the kinetic theory of matter because if the particles stay the same temperature, they will be moving at the same average speed and if the particles keep the same pressure, they will hit the sides with the same force and at the same rate. However, if you put more particles into the container, there will be more particles hitting the sides and to maintain a constant pressure, the container will have to expand according to this equation: V1/n1 = V2/n2 . In this equation, n is measured in moles, which you learned about in Unit 2 Lesson 4. Remember that 6.02 x 1023 particles are equal to one mole. Sometimes you might be given information about the amount of particles in grams and you will have to use dimensional analysis and the molar mass to switch from grams to moles. When solving a problem with this formula, your units for pressure for V1 and V2 need to be the same, too. If you are given two different units, change one unit into the other before applying the formula.

Watch a video explaining Avogadro’s Law & some worked example problems^[1]. In your notes, write down one thing you learned from the video.

Here is a worksheet to practice problems using Avogadro’s Law

Here is a link to online practice problems using Avogadro’s Law^[2]