Unit 2 Test ESSAY QUESTION Chemical Weathering.

Question

Water plays an important role in the chemical weathering of rock. In 4+ sentences, identify and explain two agents of chemical weathering to support that statement.

Complete the sentences below AND CITE THIS SOURCE IN YOUR PARAGRAPH. Unit 2 Lesson 4, Page 3

Fill-in-the-blank Sentences – Copy/paste these with your answers into the essay box on the test. Be sure to copy the Source, too! Cite your source: U2L4 PAGE 3
I chose ______ and _____ as the two types of chemical weathering that I want to discuss.
The first process is __________. Here is what happens: ___(2-3 sentences)____.
The second process I chose is __________. Here is what happens: __(2-3 sentences)___.
Cite your source: Source: Unit 2 Lesson 4, Page 3

UNIT 2 LESSON 4 PAGE 3:
"Agents of Chemical Weathering Rocks break down through both chemical and mechanical weathering. Water is the most important agent of chemical weathering. It dissolves some minerals, such as halite, through the process of dissolution. Water is needed for hydrolysis reactions, in which it breaks apart other molecules and causes decomposition and the production of new substances. What is the definition of dissolution? Answer: a reaction in which substances disintegrate in water What is the definition of hydrolysis? Answer: the breaking apart of molecules by water Water is also the conduit for other agents of chemical weathering including oxygen, carbon dioxide, and acid. For example, oxygen atoms from air or water give up electrons to other elements like copper or iron in a process called oxidation. New compounds form as a result. In the case of iron, the new substance is iron oxide, or rust. In the case of copper the new compound is copper oxide. Carbon dioxide mixes with water to form carbonic acid through carbonation. What is the definition of oxidation? Answer: the gaining of oxygen electrons to form new substances What is the definition of carbonation? Answer: the chemical reaction of carbon dioxide and water Cross Connections: Energy and Matter As a result of chemical weathering, transformations of matter are taking place. The amount of matter is conserved after the chemical reactions that cause chemical weathering."

Answer 1

I chose dissolution and oxidation as the two types of chemical weathering that I want to discuss. The first process is dissolution. Here is what happens: In this process, water dissolves certain minerals in rocks, such as halite, effectively breaking them down and carrying away the dissolved particles. This leads to the weakening of the rock structure, making it more susceptible to further weathering and erosion.

The second process I chose is oxidation. Here is what happens: In oxidation, water facilitates the reaction where oxygen atoms from the atmosphere or water react with minerals in rocks, such as iron, causing them to lose electrons and form new compounds like iron oxide, more commonly known as rust. This transformation alters the chemical composition of the rock, promoting further breakdown and contributing to the overall process of chemical weathering.

Cite your source: Source: Unit 2 Lesson 4, Page 3