Avogadro’s Law

Avogadro’s Law asserts that equal amounts of all gases contain the same number of molecules at the same pressure and temperature. Amedeo Avogadro, an Italian scientist and physicist, first proposed the concept in 1811.

At the same pressure and temperature, equivalent amounts of gas contain the same quantity of molecules, according to Avogadro’s hypothesis. As a result, the volume of a gas is proportional to the number of moles in the gas.

Ideal Gas Law:

A theoretical gas composed of a huge number of randomly drifting particles without any interparticle interactions is known as an ideal gas. Because it obeys the ideal gas law, a simplified equation of state, and is susceptible to statistical mechanics analysis, the ideal gas notion is valuable. If the interaction is fully elastic or considered as a point-like collision, the condition of zero interaction can typically be disregarded.

A fictional gas composed of components that follow a set of criteria is referred to as an “ideal gas.”

1. Ideal gas molecules are neither attracted nor repellent to one another. The sole interaction between perfect gas molecules would be an elastic collision when they collided with each other or with the container’s walls.

2 Gas molecules in their ideal state have no capacity of their own. Because the molecules extend throughout a broad span of space, the gas takes up volume, yet the Ideal gas molecules are represented as point particles with no volume in and of themselves.

Equation of Ideal Gas Law:

The macroscopic and microscopic factors such as pressure, volume, and temperature determine the condition of an ideal gas.

The ideal gas equation is written as:

Where P denotes the ideal gas’s pressure.

• V is the ideal gas’s volume.

• n is the mole equivalent of the quantity of ideal gas.

• The gas constant is R.

• T stands for temperature.

This equation is derived from:

• Boyle’s law: at constant temperature, the pressure of an unit weight of an ideal gas is inversely proportional to its volume. ;

• Charles’s law: The volume of an ideal gas at relentless pressure is exactly proportional to the absolute temperature, according to the law. ;

• Avogadro’s law: Under the same temperature and pressure conditions, Avogadro’s law asserts that equal volumes of diverse gases possess an equal number of molecules. .

After combining three laws we get

That is:

What is real gas?

A true gas violates the laws of physics at all normal pressures and temperatures. As the gas grows larger and more voluminous, it departs from its optimal behaviour. The velocity, mass, and volume of the gas are all accurate. When cooled to the boiling point, they liquefy. When compared to the overall volume of gas, the amount of space used by gas is huge.

The real gas law equation is given as:

Where; are gas constants.

What is Avogadro’s Law?

Under the same temperature and pressure conditions, Avogadro’s law asserts that equal volumes of diverse gases contain an equal number of molecules. Under the assumption of a perfect (ideal) gas, the kinetic theory of gases may be utilized to derive this empirical relationship.

Avogadro’s Law Formula:

At constant pressure and temperature, it can be expressed as:

Here,

• is the volume of gas 

• is the amount of gaseous substance in moles 

• is a constant

Graphically, it can be shown as:

Examples:

1. Breathing

The finest potential demonstration of Avogadro’s law is human lungs. The lungs expand as we inhale because they are filled with air. Exhaling, on the other hand, causes the lungs to let go of air and shrink in size.

2. Inflating a Ball

A bladder and a stiff outer shell are both found within a soccer ball. The bladder loses its form and becomes deflated as the ball is deflated, causing the ball to lose its capacity to bounce. By forcing air into the bladder with an air pump, the volume of air inside the bladder may be raised.

3. Bicycle Pump Action 

Avogadro’s law is used in the action of a bicycle pump. The pump draws air from the surrounding environment and forces it into a deflated item. As the number of gas molecules in the thing increases, the object’s form changes as it expands. Avogadro’s law describes the relationship between the number of air molecules and the volume.

Limitation of Avogadro’s law:

• The rule is only valid for ideal gases.

• For actual gases at low pressure and/or high temperature, the rule is approximate.

• Real gases have a somewhat higher volume-to-mole ratio than ideal gases at low temperatures and/or high pressures. This is related to the expansion of actual gases under high pressure owing to intermolecular repulsion forces.

Conclusion:

Avogadro’s law, also known as Avogadro’s principle or Avogadro’s hypothesis, is a gas law that asserts that given constant temperature and pressure, the total number of atoms/molecules in a gas (i.e. the amount of gaseous material) is directly proportional to the volume occupied by the gas.