In this lesson, we will explore the properties of gases and the laws that govern their behavior. We will cover the following topics:
The Kinetic Molecular Theory (KMT) is a model that helps explain the behavior of gases. According to KMT, gases consist of particles (molecules or atoms) that are in constant, random motion. The key postulates of KMT are:
Pressure is the force exerted by gas particles per unit area. It is measured in units such as atmospheres (atm), pascals (Pa), or millimeters of mercury (mmHg). The pressure of a gas depends on the number of particles, the temperature, and the volume of the container.
The behavior of gases can be described by several laws that relate pressure, volume, temperature, and amount of gas. These laws are empirical relationships based on experimental observations.
Boyle's Law states that the pressure and volume of a fixed amount of gas at constant temperature are inversely proportional. Mathematically, P₁V₁ = P₂V₂, where P is pressure, V is volume, and the subscripts 1 and 2 represent two different states.
Charles's Law states that the volume of a fixed amount of gas at constant pressure is directly proportional to its absolute temperature. Mathematically, V₁/T₁ = V₂/T₂, where V is volume, T is absolute temperature, and the subscripts 1 and 2 represent two different states.
Gay-Lussac's Law states that the pressure of a fixed amount of gas at constant volume is directly proportional to its absolute temperature. Mathematically, P₁/T₁ = P₂/T₂, where P is pressure, T is absolute temperature, and the subscripts 1 and 2 represent two different states.
The Ideal Gas Law combines the relationships between pressure, volume, temperature, and amount of gas into a single equation: PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the ideal gas constant (8.314 J/mol·K), and T is absolute temperature.
In the next section, we will apply these concepts to solve problems related to gases.