Charles’s Law

In this unit, you will learn the Gas Law: Charles’s Law which describes how gases behave. This law along with some other well known gas laws are important because they allow you to predict how 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 moves 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 Charles’s Law  in detail:

What is Charles’s Law?

Charles’ Law, often known as the law of volumes, describes how a gas expands as the temperature rises. On the other hand, a reduction in temperature will result in a decrease in volume.

When comparing a material under two distinct situations, we may write the following from the previous statement:

Charles’s Law formula

V2/V1= T2/T1

OR

V1.T2=V2.T1

This Charles’s Law formula shows that when the gas’s absolute temperature rises, the volume of the gas rises in proportion.

To put it another way, Charle’s law is a variant of the ideal gas law. The law applies to ideal gases kept at constant pressure but has varying temperatures and volumes.

The Law’s Discovery and Naming

The rule was named after the French mathematician, physicist, inventor, and balloonist Jacques Alexandre César Charles. He made history by being the first person to launch a manned hydrogen-filled gas balloon. Natural philosopher Joseph Louis Gay-Lussac wrote a paper outlining how gases expand when heated just a few days after the first human-crewed hot air balloon flight in 1802. He attributed it to Jacques Charles’s unpublished work from the 1780s. In honour of Charles, Gay-Lussac titled the statute ‘Charles Law.’

In 1787, Charles experimented with filling five identical containers with various gases. After that, he raised the temperature of the containers to 80 degrees Celsius. He then saw that all gases had grown in volume by the same amount. Gay-Lussac mentioned this experiment in his paper from 1802. Charles deduced that the volume of gas grew linearly with the absolute temperature of that gas under constant pressure and named it as Charles law.

Charles’ Law’s Derivation

According to Charles’ Law, we know that the volume of a certain amount of dry gas is precisely proportional to absolute temperature at constant pressure. The following is a representation of the statement.

V∝T

We can use the constant k to equal V and T because they are both directly changing.

V/T = constant = k

In this case, the value of k is determined by the gas’s pressure, volume, and unit of measurement.

V/T=k——-(1)

Consider V1 and T1 as the starting volume and temperature of an ideal gas, respectively.

Charles law equation (1) can therefore be written as

V1/T1=k——-(2)

After that, we’ll alter the gas’s temperature to T2. Alternatively, if the volume switches to V2, we will write.

V2/T2=k——–(3)

Equating the two equations above (equations 2 and 3) yields

V1/T1=V2/T2

OR

V1T2=V2T1

Application of Charles Law in Real Life

1 – This law has several applications in everyday life. On the other hand, the balloon regains its shape when placed in a warm environment. What causes this to happen- If you’ve ever been outside on a cold day, you’ve probably observed that the balloon crumbles? This occurs because the volume reduces when the temperature drops on a chilly day. Now, according to Charle’s Law, the temperature rises as soon as you enter a heated room; as the temperature rises, the volume rises as well. As a result, the balloon returns to its former shape.

2- Our kitchens are no exception to Charle’s Law. If you’ve ever tried your hand at baking, you’re probably familiar with the most popular ingredient in the process: yeast. Baking yeast is commonly used to generate fluffy baked items. The release of carbon dioxide bubbles is caused by yeast. When the temperature rises, the carbon dioxide bubbles expand, acting as a leavening agent, causing the bread items to puff up. With a higher temperature, the carbon dioxide bubbles will expand even more.

Conclusion:

The formula for Charles’ Law can be understood by Boyle’s law and combined gas law. 

The mathematical version of Charles law, V1T2=V2T1, 

and the combined gas law: p1V1T1=p2V2T2, may be derived. The Charles’ Law states that the volume of a gas is directly proportional to the temperature of an isobaric process (constant pressure).