Difference Between Mechanical Weathering and Chemical Weathering (With Table)

The process of breakdown of rocks through the action of rainwater, significant temperature variations, and environmental changes are known as Weathering. Weathering can take place for various reasons. Two of these reasons are Mechanical Weathering and Chemical Weathering. The difference between these two is quite simple yet quite vast. 

Mechanical Weathering vs Chemical Weathering 

The difference between Mechanical Weathering and Chemical Weathering is that Mechanical Weathering takes place without changing the rock’s chemical composition. On the other hand, Chemical Weathering takes place by changing the chemical composition of the rocks altogether. The agents that cause these changes of the rocks’ breakdown are different from each other, and so are the geographical locations of Mechanical Weathering and Chemical Weathering weathering processes. 

Mechanical weathering is the mechanism by which the crackup of rocks occurs without altering the rock’s chemical composition.  The most common type of mechanical weathering happens through freeze-thawing weathering.

It affects the coasts the most when rocks are porous. Water makes its way into the rocks, and the porosity of these rocks freezes the water inside. The ice makes the rock expand and cracks.

The means through which the crackup of rocks happens due to changing their chemical composition is Chemical weathering. When rainwater reaches the rock, this process begins, and it gets decomposed, or the rock gets eaten away. 

This process is called carbonation. This only happens when a little acidic or carbonic rain or water from the sea gets into touch with sedimentary rock, for example, limestone or chalk, it makes it evaporate.

 A chemical reaction occurs between the acidic water and the calcium carbonate, which turns it into calcium bicarbonate. This makes it soluble and is taken away in solution. This type of weathering takes place in heated, wet conditions. 

Comparison Table Between Mechanical Weathering and Chemical Weathering

Parámetros de comparaciónMechanical WeatheringChemical Weathering
DefiniciónIn mechanical weathering, the chemical composition does not change.In chemical weathering, the chemical composition changes.
Geographic LocationsIt takes place in hot and dry conditions, as the temperature keeps on changing throughout the day.Chemical weathering takes place in regions that have a hot and humid climate.
AgentsThe main agents of mechanical weathering are running water, temperature, winds, and moisture.The main agents of chemical weathering are hydration, carbonation, oxidization, and solution.
AfectarThis type of weathering affects rocks deeply to a very great extent.This type of weathering takes place only on the surface of the earth.
ResultadoMechanical Weathering breaks rocks into smaller parts without changing the composition of the rocks.Chemical Weathering takes place by breaking down rocks by creating new minerals at the top of the earth’s surface.

What is Mechanical Weathering?

Mechanical weathering, also known as physical weathering and disaggregation, makes rock break down into smaller pieces. The main reason why mechanical weathering occurs in rocks is water, which may be in liquid or solid form.

To elaborate further, liquid water can trickle into cracks of the rocks and makes its way in. Later, if the area’s temperature goes down, the water in the rocks gets frozen, which makes the rock expand and crack. 

The ice then plays the role of a catalyst. It gradually stretches up the cracks of the stones and divides the rock. When ice thaws, liquid water completes the process of weathering by moving away the little tiny stone scraps lost in the fissure. This particular process (the freeze-thaw cycle) is known as cold weathering. 

Temperature changes can also add to mechanical weathering in a manner known as thermal stress: variations in heat cause rock to expand (with heat) and contract (with cold). The formation of the rock crumbles after a certain amount of time. After a specific amount of time passes, the rocks start to crumble into smaller pieces.

What is Chemical Weathering?

Chemical Weathering is the principle through which the breakdown of rocks happens because of chemical reactions transpiring around the minerals present in stones and the atmosphere. The main agents of chemical weathering are water.

A lot of synthetic compounds are found in water. Water has many weak acids, such as carbonic acid, which leak into the rocks to start the breaking down process.

This vulnerable acid is enough to be formed when carbon dioxide gas from the environment mixes with rainwater. Sulfur dioxide and nitrogen gases form other varieties of acid rain that perform as chemical weathering catalysts.

Few origins of sulfur dioxide are power plants that incinerate coal, and some also originate from volcanoes and coastal marshes. These sulfur gases eventually come in contact with oxygen and rainwater to create sulfuric acid.

The acid has plentifulness and long duration impacts that create quite a bit of havoc to vegetation and rocks, even though it is very weak. Oxidation is an unconventional type of chemical weathering that occurs when oxygen combines with another substance and creates compounds called oxides.  

Main Differences Between Mechanical Weathering and Chemical Weathering

  1. Mechanical Weathering does not change the chemical composition of the rocks and stones, while on the other hand, Chemical Weathering will change the entire chemical composition of the rocks. 
  2. Mechanical Weathering takes place in hot and dry climates. In contrast, Chemical Weathering takes place in hot and humid conditions.
  3. The main agents of mechanical weathering are water, temperature, moisture, etc. The main agents of chemical weathering are oxidation, solution, carbonation as well as hydration. 
  4. Mechanical Weathering affects the rock to great depths. On the other hand, the effects of chemical weathering are only on the surface of the earth. 
  5. Mechanical Weathering will break the rocks down into smaller pieces, and on the other hand, Chemical Weathering happens by forming new minerals on the top of the surface. 

Conclusión

Mechanical Weathering and Chemical Weathering are both mind-blowing ways through which the earth decompresses and erodes the surface. Mother nature incredibly shows us how she can dissolve, breakdown rocks, and form new minerals out of them. This magical process of weathering then is later followed by erosion which takes away these minerals and rocks to a different place, affecting nature and everyone in turn. The differences between these two types of weathering or erosions are straightforward to look out for if the primary agents are kept in mind. 

Referencias

  1. https://www.nationalgeographic.org/encyclopedia/weathering/#:~:text=Mechanical%20weathering%2C%20also%20called%20physical,enough%2C%20the%20water%20will%20freeze.