Physical vs. Chemical Change Quick Check Answers 9A
1. Which of the following is an example of only a physical change?
(Answer) dry ice becoming vapor
2. Which of the following demonstrates a chemical change?
(Answer) iron (Fe) reacting to water ((H2O)) and oxygen(O) to form iron oxide (Fe2O3)
3. Which of the following is a reliable way to observe that a chemical change has occurred when two substances come in contact with one another?
(Answer) conduct a test to determine the chemical makeup of the molecules
4. Which of the following happens during a chemical change but does not happen during a physical change?
(Answer) Atoms of one or more substances rearrange into a new substance.
5. Which of the following example demonstrates the reversibility of a chemical change?
(Answer) recharging batteries
To answer these questions, you need to have a basic understanding of the differences between physical and chemical changes.
1. To identify an example of only a physical change, you need to know that a physical change does not involve the formation of a new substance. In this case, dry ice becoming vapor is an example of a physical change because it is still the same substance (carbon dioxide) just in a different state (from solid to gas).
2. To identify a chemical change, you need to know that a chemical change involves the formation of a new substance with different properties. In this example, iron reacting with water and oxygen to form iron oxide is a chemical change because a new substance (iron oxide) is formed.
3. To reliably observe that a chemical change has occurred when two substances come in contact with each other, you need to conduct a test to determine the chemical makeup of the molecules. This could involve using chemical testing methods, such as chemical tests or spectroscopy, to analyze the composition of the substances before and after the reaction.
4. To identify what happens during a chemical change but not during a physical change, you need to know that atoms of one or more substances rearrange into a new substance. In a physical change, the arrangement of atoms remains the same, whereas in a chemical change, the arrangement changes, resulting in the formation of new substances.
5. To identify an example that demonstrates the reversibility of a chemical change, you need to know that not all chemical changes are reversible. In this case, recharging batteries is an example of the reversibility of a chemical change because a chemical reaction occurs during the discharge of the battery, and that reaction can be reversed by recharging the battery.
1. The example of dry ice becoming vapor is an example of only a physical change.
2. The reaction of iron (Fe) with water (H2O) and oxygen (O) to form iron oxide (Fe2O3) is an example of a chemical change.
3. A reliable way to observe that a chemical change has occurred when two substances come in contact with one another is to conduct a test to determine the chemical makeup of the molecules.
4. During a chemical change, atoms of one or more substances rearrange into a new substance, which does not happen during a physical change.
5. The example of recharging batteries demonstrates the reversibility of a chemical change.
1. Why did the chicken go to school?
Because it wanted to be an "eggucated" fowl!
2. Why did the scarecrow win an award?
Because he was outstanding in his field!
3. What do you call fake spaghetti?
An impasta!
4. Why don't scientists trust atoms?
Because they make up everything!
5. What did one ocean say to the other?
Nothing, they just waved!