Unit 2: Gas Laws

Gas laws | Name: … | Date: 09/08/2023 | Class period: 1

Gas laws (created in the early 17th century) consist of three primary laws: Charles’ Law, Boyle’s Law and Avogadro’s Law (all of which will later combine into the General Gas Equation and Ideal Gas Law).

Objectives

• Explain the factors that affect gas pressure.
• Describe real-world experiences and how they relate to gas pressure, temperature, and volume.
• Predict the behavior of a gas by changing one of its variables.

OBJ 1: Introduction & Review (Kinetic Molecular Theory)

1. KMT makes three major assumptions about the particles in a gas:

1. Their particles move in a straight line until they collide with other particles or the walls of their container.
2. The motion of the particles is constant and random.
3. There are no attractive or repulsive farces among the particles.

2. Four variables are generally used to describe a gas:

1. Pressure (kPA, mottG, atm-use this often)
2. Volume (L or mL)
3. Temperature (always in Kelvin, no negative numbers)
4. Amount (moles)

3. Factors Affecting Gas Pressure – Effect of adding or removing gas

1. When the amount of gas in a given volume is increased, pressure increases. Example: Doubling amount of gas.
2. More particles means more collisions, which means more pressure.
3. This is a direct relationship: If the number of particles double, pressure doubles.

4. Factors Affecting Gas Pressure – Effect of changing volume of container

When the volume of a gas is decreased (for a given amount of gas), pressure increases. Example: Decreasing volume by half

• Particles are closer together in a container; which means more collisions, which really means more pressure!
• This is an indirect relationship: If the volume is halued, pressure is doubled and vice-versa.

5. Factors Affecting Gas Pressure – Effect of changing temperature

When the temperature of a gas increases, the particles have more KE, and pressure increases. Example: Doubling temperature

• The particles move faster when heated, and strike the walls of the container with more force; so the pressure builds.
• This is a direct relationship: If the temperature is doubled, pressure is doubled and vice-veresa.

6. STP: stands for Standand Temperature and Pressuce

• Pressure: 101.3 kPa; 760 mmHg; 14.7 psi ; 1 atm
• Temperature: 273 Kelvin or 0°C – but change it to Kelvin