Final answer:
Mechanical weathering involves physical breakdown of rocks, while chemical weathering involves alteration of their composition through chemical reactions. Mechanical weathering does not affect the composition of rocks, occurs worldwide, and can involve water. Chemical weathering affects composition, can be influenced by various factors, and often requires water for reactions.
Step-by-step explanation:
Definition:
Mechanical weathering is the physical breakdown of rocks into smaller pieces without changing their chemical composition. It occurs through processes like freeze-thaw cycles, abrasion, and root wedging. Chemical weathering, on the other hand, involves the alteration of rock's composition through chemical reactions such as oxidation, hydration, and hydrolysis.
Differences:
Mechanical weathering does not affect the composition of rocks, while chemical weathering does. Mechanical weathering can occur in any part of the world, but the rate of weathering can be influenced by factors like climate and rock type. Both types of weathering can involve water, with chemical weathering often requiring the presence of water for chemical reactions to occur.
Examples: A rock breaking apart into smaller pieces due to the expansion of freezing water is an example of mechanical weathering. The gradual decomposition of limestone due to the reaction with rainwater is an example of chemical weathering.
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