What is the difference between effusion and diffusion?

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Table of Contents Show

Key Areas Covered
What is Diffusion
What is Effusion
Type of Molecules
Type of Movement
Driving Force
What is the Difference Between Effusion and Diffusion?
Examples of Diffusion and Effusion
Interesting Facts
Key Features to Remember

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The main difference between diffusion and effusion is that diffusion is the movement of particles through a concentration gradient whereas effusion is the movement of gas molecules through tiny holes. Furthermore, diffusion describes the movement of solid, liquid, and gas molecules while only gases undergo effusion.

Diffusion and effusion are two methods used by different molecules to move from one to another place. Furthermore, Graham’s law describes the relationship between the rate of diffusion or effusion and the molar mass of gases.

Key Areas Covered

1. What is Diffusion
– Definition, Driving Force, Efficiency
2. What is Effusion
– Definition, Driving Force, Efficiency
3. What are the Similarities Between Diffusion and Effusion
– Outline of Common Features
4. What is the Difference Between Diffusion and Effusion
– Comparison of Key Differences

Key Terms

Concentration Gradient, Diffusion, Effusion, Gas, Liquids, Movement of Molecules, Solids

What is Diffusion

Diffusion is a type of movement of molecules through a concentration gradient. It can occur in all three types of molecules including solids, liquids, and gases. The main importance of diffusion is that it allows the mixing of molecules with each other in the space in the absence of a barrier. However, it mainly occurs due to the concentration gradient of molecules. But, it depends on the size and the kinetic energy of molecules.

Figure 1: Diffusion

When considering gases, diffusion is the thermal random motion of molecules. Here, collisions that occur among gas molecules allows the release of molecular energy of the gas. Therefore, it becomes one of the major factors in reducing the efficiency of diffusion.

What is Effusion

Effusion is a type of movement of gas molecules. It occurs with the escape of gas molecules through a pinhole into a vacuum. In simple terms, it describes the ability of gas molecules to move through a small opening. Here, the opening has to be smaller than the mean free path of the molecules.

Figure 2: Effusion

Furthermore, the concentration gradient of gas molecules between either side of the opening generates a pressure gradient across the opening. And, this pressure gradient serves as the major driving force which moves the gas molecules from the higher concentration of gases to a lower concentration through the opening.

Diffusion and effusion are two mechanisms used by different types of molecules to move one to another place.
Both methods occur through a concentration gradient.
Moreover, the flow of molecules is constant and random.
Besides, both do not use energy for the movement of molecules.

Diffusion refers to the net passive movement of particles (atoms, ions, or molecules) from a higher concentration region to a lower concentration region. Effusion refers to the movement of gas particles through a small hole. Thus, this is the main difference between diffusion and effusion.

Type of Molecules

Another major difference between diffusion and effusion is that diffusion occurs in solid, liquid, and gas molecules while effusion occurs only in gas molecules.

Type of Movement

Also, molecules move freely throughout space in diffusion while the movement of molecules occurs through tiny holes in effusion.

Driving Force

Furthermore, the concentration gradient is the driving force in diffusion while the concentration gradient of gases generates a pressure gradient in effusion.

Collision

One other difference between diffusion and effusion is that the collisions occur among the molecules in diffusion while there is no collision among the molecules in effusion.

Efficiency

Moreover, diffusion is a less efficient method while effusion is more efficient due to the pressure difference involved in the process.

Conclusion

Diffusion is the movement of molecules through a concentration gradient. Solid, liquid, and gas molecules use this method. On the other hand, the effusion is the movement of gas molecules through a concentration gradient, especially, through tiny holes. It is a highly efficient method due to the pressure gradient involved in the process. Therefore, the main difference between diffusion and effusion is the barrier which filters the gas.

References:

1. “Diffusion and Effusion|Boundless Chemistry.” Lumen Learning, Lumen, Available Here

Image Courtesy:

1. “Diffusion” By JrPol – Own work (CC BY 3.0) via Commons Wikimedia
2. “Effusion” By Astrang13 – Own work (CC BY-SA 3.0) via Commons Wikimedia

Diffusion and effusion in Chemistry are the two most common concepts to refer to two distinct properties of gases. Diffusion and effusion may have a similar sound, but they are completely separate concepts. They cannot be used interchangeably since they have different interpretations. However, both effusion and diffusion are phenomena that take place every day of human existence. Human bodies typically experience diffusion, which involves the transportation of oxygen, vitamins, and energy.

Whenever a certain amount of gas attempts to move from one area to another, a barrier generally seems to be present or missing, which is the main difference between effusion and diffusion. But first, let's examine how diffusion and effusion differ from one another.

What is the Difference Between Effusion and Diffusion?

A sort of molecular motion via a gradient of concentration is called diffusion. The primary significance of diffusion is that it enables the combining of molecules in the absence of a boundary. But it primarily happens because of the gradient in molecular concentrations. Diffusion of gas occurs from high concentration regions to low concentration regions.

The motion of gas molecules is known as effusion. In a vacuum, it happens when gas molecules depart via a keyhole. It explains how easily gas molecules can pass via a small aperture in plain ways. The aperture in this case needs to remain smaller than the molecules' average free passage. Gas molecules will gradually but steadily move through the hole.

Examples of Diffusion and Effusion

The movement of carbon dioxide, water, urea, oxygen, and ethanol, the smell of perfume, or the foods inside a closed room are a few examples of diffusion. Substances in the body which can quickly diffuse through and outside of the cell membrane. Without utilizing any energy, they transport the concentration gradient right over the cell membrane.

An effusion is a deposition of fluid in an anatomical region, typically without loculation, according to medical terms. Pericardial, subdural, and pleural effusions are specific examples of effusion.

Balloons can be used to observe effusion. Despite the fact that the balloon appears to be completely impenetrable, effusion shows that it has holes in it. A helium-filled balloon will inevitably collapse if left aside for numerous days. That balloon would collapse faster if it were loaded with hydrogen since the molecules are more easily able to escape due to their smaller size.

The difference between diffusion and effusion in chemistry is provided in the below tabular column.

Diffusion	Effusion
Diffusion occurs when one gas interacts with another, typically through thermal movement of particles, causing collisions that release molecular energy.	Effusion happens through gas particles’ movement via a tiny hole.
Diffusion movement takes place throughout space without any boundaries	Only a very small hole allows molecules to move.
Gas molecules colliding with one another causes the gas's molecular energy to be released.	No collision takes place within the molecules.

Interesting Facts

Apart from differences there are some similarities between diffusion and effusion, a concentration gradient is utilized in both diffusion and effusion.
The movement of molecules is also continuous and random in diffusion and effusion. Furthermore, neither one requires energy to move molecules.
The Latin term diffundere, which signifies "to spread out," is the root of the English term diffusion.
The Latin term effundo, which signifies "shed, pour out, waste, utter, lavish," is the source of the English term effusion.

Key Features to Remember

The gas molecules which constantly move randomly, can cause diffusion. It is known as Brownian Motion. Ultimately, the molecules will travel wherever they can. The capacity of the gases to mix without requiring a larger movement is referred to as diffusion.
The molecules' constant random motion also explains effusion. The capacity of gases to move via a tiny opening and from a location with a greater content to a smaller content is referred to as effusion, on the contrary.
Furthermore, the boundary that screens the gas is the primary difference between diffusion and effusion.