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Introduction
In this unit, you will learn the four gas Laws, namely Boyle’s Law, Charle’s Law, Gay-Lussac’s Law and Avogadro’s Law which describe how gases behave. These laws are important because they allow you to predict how a gas will react if you change its temperature or pressure.
These laws have been used for centuries to describe gases and predict their properties. Most importantly, you’ll see how gas laws can be used to answer questions about the properties of gases that are difficult or impossible to observe. In addition, you’ll learn some of the strange behaviour of gases that can be hard to follow without some background knowledge of physics.
Gas laws
The gas laws are the most fundamental laws of thermodynamics. They describe how the energy levels of atoms and molecules change with temperature, pressure, and chemical environment. They also describe how these change when a system is moving from one state to another. These laws are often used to predict the properties of a material when it is under certain conditions. Let us discuss a few gas laws in detail:
Boyle’s Law
Boyle’s law is an important thermodynamic principle that describes the relationship between the pressure and temperature of a gas proportional to the increase in the volume of the gas. The principle can be stated simply as follows: The pressure and temperature of an ideal gas are inversely proportional to each other. This means that as the pressure of a gas is increased, its temperature is decreased, and as the temperature of a gas is increased, its pressure is decreased. This statement is what constitutes Boyle’s law.
Charles’s Law
Charle’s law, which is a gas law, states that in ideal gas mixtures, the pressure is inversely proportional to the volume of a gas. The law is named after the chemist, Robert Charles (Charles) Lilienfeld, who first published it in 1847. Charle’s law is important in several fields of science, including astronomy, aviation, chemistry, and chemistry. In order to satisfy Charle’s law, the density of the gas must be constant.
Gay-Lussac’s Law
Gay-Lussac came up with a new gas law in 1774, which stated that gases at the same temperature and pressure exerted the same pressure, regardless of their composition. He discovered this law during a laboratory experiment involving gases of different temperatures and pressures. He found that the pressure and temperature of the gas were not directly proportional to one another, which led him to conclude that the pressure and temperature of the gas were directly proportional to one another only if they were the same for all of the gases in the mixture. This idea is what constitutes Gay-Lussac’s law.
Avagadro’s Law
Avagadro’s law states that the number of molecules in a gas is proportional to the temperature and inversely proportional to the volume. Avagadro’s law is used in various fields and industries, and in chemistry is known as the law of constant proportion as it relates to the mole.
Mathematical expression of Boyle’s law
The mathematical expression of Boyle’s law is a constant pressure and constant volume, which can be expressed as: P V = k, where P is pressure, V is volume and k is a constant. This means that for a constant pressure, a constant volume must be maintained. This law can be seen in the illustration of a column of air, where the pressure at the base increases as the column expands, while the pressure at the top remains constant. This demonstrates that as the volume of a substance increases, the pressure within the substance also increases.
Boyle’s Law is a statement of the relationship between the pressure and volume of a gas, which can be written as the constant pressure of gas multiplied by the constant volume of gas. The law is often written as: P1V1 = P2V2, where P1 is the pressure, V1 is the volume, and P2 is the pressure of the gas, V2 is the volume of the second gas, and n is the constant of proportionality. The law can also be written as: P1V1 = kPa.
Strange behaviour of gases:
- Some gases in common air are invisible, like nitrogen and carbon dioxide. Others are visible, like oxygen and water. However, many other gases like carbon monoxide are still poisonous.
- The way gases absorb light is also strange. You’ve probably seen this behaviour in action. When you hold your hand over a bright light, such as the light from a torch, a candle or the sun, you can see the light being absorbed by your hand.
Conclusion
Experiments and observations in physics have led to the development of four fundamental principles that describe how gases behave: the law of Boyle, the law of Charles, avagadro’s law and the law of Gay-Lussac. The experiments and observations described in this section have led to the development of the gas laws. These laws are most useful in explaining the behaviour of gases under constant pressure and constant temperature. We’ve further discussed Boyle’s law and its mathematical expression that is P1V1 = P2V2.
