Unit 7 - Chemical Reactions And Energy
Chemical reactions are the processes that lead to the transformation of one set of chemical substances to another. Energy is a physical property that must be transferred to an object in order to perform work on or to heat it.
- 1.
Which of the following is a chemical reaction?
- A.
Rust forming on a car body
- B.
Water evaporating from salt water leaving salt crystals
- C.
Water freezing into ice
- D.
Dew forming on grass
Correct Answer
A. Rust forming on a car bodyExplanation
Rust forming on a car body is a chemical reaction because it involves a chemical change. Rust is formed when iron reacts with oxygen in the presence of moisture, resulting in the formation of iron oxide. This process is known as oxidation and is a chemical reaction.Rate this question:
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- 2.
When iron combines with oxygen and water in the air to form rust, what substance in the reaction is the product?
- A.
Rust
- B.
Iron
- C.
Oxygen
- D.
Water
Correct Answer
A. RustExplanation
When iron combines with oxygen and water in the air, it undergoes a chemical reaction to form rust. Rust is the product of this reaction, which means it is the substance that is produced as a result of the reaction.Rate this question:
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- 3.
As a result of the experiment of Lavoisier, you know that in a chemical reaction the mass of the products ______.
- A.
Is twice as great as the mass of the reactants
- B.
Is less than the mass of the reactants
- C.
Always equals the mass of the reactants
- D.
Cannot be predicted based on the mass of the reactants
Correct Answer
C. Always equals the mass of the reactantsExplanation
In the experiment conducted by Lavoisier, it was observed that the mass of the products formed in a chemical reaction is always equal to the mass of the reactants. This observation is known as the law of conservation of mass, which states that mass is neither created nor destroyed in a chemical reaction. Therefore, the correct answer is that the mass of the products always equals the mass of the reactants.Rate this question:
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- 4.
Which of the following symbols in a chemical equation means "produces"?
- A.
+
- B.
[p]
- C.
(aq)
- D.
![Unit 7 - Chemical Reactions And Energy - Quiz]()
Correct Answer
D.Explanation
The symbol "+" in a chemical equation means "produces".Rate this question:
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- 5.
A(n) ______ is a substance that speeds up a chemical reaction without being permanently changed itself.
- A.
Catalyst
- B.
Inhibitor
- C.
Exotherm
- D.
Endotherm
Correct Answer
A. CatalystExplanation
A catalyst is a substance that speeds up a chemical reaction without being permanently changed itself. It works by lowering the activation energy required for the reaction to occur, allowing the reaction to proceed at a faster rate. Catalysts can be used in various industries such as the production of chemicals, pharmaceuticals, and energy. They are essential in increasing the efficiency and reducing the cost of many chemical processes.Rate this question:
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Mar 21, 2023Quiz Edited by
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Jan 10, 2013Quiz Created by
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