Gas Laws Chemistry

Introduction

Several laws governing the temperature, pressure, and volume of a gas form the rules of gas. These rules determine the behaviour of gases and are governed by certain related factors. The limits attached to gas laws are as follows.

• The full volume of gas.
• Pressure release of gas from vessel walls.
• The total temperature of the gas.
• The number of moles present in electricity or the number of electrical objects.

What are Gas Laws?

Toward the end of the 18th century, a number of scientists developed some gas laws. Each gas law is identified by the names of the scientists who submit it. So, today we notice five important gas laws like this.

• Boyle’s law provides for the relationship between pressure and gas volume.
• Charles’ law provides the relationship between gas volume and total gas temperature.
• Gay-Lussac law provides for the relationship between the pressure emitted by the gas in the walls of its container and the total temperature associated with the gas.
• Avogadro Act provides for the relationship between gas volume and gas price.

Combined Gas Law, also known as good gas law, can be obtained by combining the above four rules each given by four different scientists. Although the combination of these laws defines positive gas behaviour, it measures the behaviour of real gases very closely.

All gases behave in the same way under normal conditions. As physical boundaries change, their diversity of behavior is noticed. These body components include temperature, pressure, and gas volume. Changes in these parameters create behavioural changes in gases. Therefore, gas laws define these changes in gas behavior.

Now let’s look at gas laws and understand their various uses.

Boyle’s law

As mentioned above, Boyle’s Law defines the relationship between gas pressure and gas volume, at a constant temperature. Therefore, it actually means that the volume of the gas is equal to the pressure of the gas at a constant temperature.

It can also be given to the equation mentioned below

V ∝ 1/P

Or,

P ∝ 1/V

Or,

PV = k₁

Where,

V gives the volume of the gas.

P gives the pressure of the gas.

K₁ is the constant.

Therefore, Boyle’s law can also be formulated as shown below, also to calculate the pressure or volume of a given gas, at a constant temperature.

P₁V₁ = P₂V₂

Charle’s Law

According to Charle’s law, the volume of a gas is directly proportional to its temperature (in Kelvin) in a closed system. Therefore this law also explains the relationship between the temperature and volume of the gas.

Charle’s law can be expressed by the formula as shown below.

V ∝ T

Where V gives the volume of gas,

T gives the temperature of the gas in Kelvin,

This equation can also be written as,

V₁ / T₁ = V₂ / T₂

Additionally V₁ / T₁ = V₂ / T₂

⇒ V/T = constant= K₂

So, V= K₂T.

Thus, the value of K₂ depends on the pressure of the gas, its amount, and also on the unit of volume.

Gay-Lussac Law

Gay-Lussac gas law gives a relationship between the temperature and gas pressure, with a constant volume. This means that with a constant volume, the gas pressure is directly proportional to its temperature.

For example, when you heat a gas, the molecules in it absorb energy and move faster. In cooling, temperature and pressure changes can be calculated using Gay-Lussac law.

This is mathematically expressed as follows.

P ∝ T

Or,

P / T = k₁

Or,

P₁ / T₁ = P₂ / T₂

where P is the pressure of the gas.

T is the temperature of the gas in expressed in Kelvin.

FAQ’s:

Q. The pressure exerted by a gas in container 1 is 3 kPa. When container 1 is emptied into a 10-litres container, the pressure exerted by the gas increases to 6 kPa. Find the volume of the container ?

Ans: 1. Let’s consider that the temperature and quantity of the gas remains constant

Given,

Initial pressure, P₁ = 3 kPa

Final pressure, P₂ = 6 kPa

Final volume, V₂ = 10L

According to Boyle’s law, V₁ = (P₂V₂)/P₁

V1 = (6 kPa * 10 L)/3 kPa = 20 L

Therefore, the 20 L is the volume of container 1.

Q. Determine the change in pressure when a constant volume of gas at 2.00 atm is heated from 30.0 °C to 40.0 °C ?

Ans:

P₁T₁ = P₂T₂

P₂ = 626.3/303.15

P₂ = 2.0659