Reaction 1

Question

*video of someone putting silver nitrate with hci in water*

what type of change has taken place?

physical change

chemical change

In 2-3 sentences, in your own words, describe why you chose that type of change in the previous question. Key points you may include in your response:
. the definition of physical/chemical change
. the start/end products in a physical/chemical change
. the start/end appearance in a physical/chemical change
. the particular visible evidence observed to indicate a physical/chemical change.
100 word limit

Reaction 2
*a video of a 1969 copper penny reacting with concentrated nitric acid*

what type of change has taken place?
physical change

chemical change

In 2-3 sentences, in your own words, describe why you chose that type of change in the previous question. Key points you may include in your response:
. the definition of physical/chemical change
. the start/end products in a physical/chemical change
. the start/end appearance in a physical/chemical change
. the particular visible evidence observed to indicate a physical/chemical change.
100 word limit

Reaction 3
*a time lapse video of a glass of water freezing outside*

what type of change has taken place?
physical change

chemical change

In 2-3 sentences, in your own words, describe why you chose that type of change in the previous question. Key points you may include in your response:
. the definition of physical/chemical change
. the start/end products in a physical/chemical change
. the start/end appearance in a physical/chemical change
. the particular visible evidence observed to indicate a physical/chemical change.
100 word limit

Reaction 4
*a time lapse video of an apple rotting*

what type of change has taken place?
physical change

chemical change

In 2-3 sentences, in your own words, describe why you chose that type of change in the previous question. Key points you may include in your response:
. the definition of physical/chemical change
. the start/end products in a physical/chemical change
. the start/end appearance in a physical/chemical change
. the particular visible evidence observed to indicate a physical/chemical change.
100 word limit

Answer 1

Reaction 1
Type of Change: Chemical change
A chemical change occurs when substances transform into different substances with distinct chemical properties. In this reaction, silver nitrate and hydrochloric acid combine to form silver chloride (a precipitate), which indicates a new product has formed. The appearance change is noticeable as a solid precipitate appears in the solution, demonstrating a chemical reaction.

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Reaction 2
Type of Change: Chemical change
I chose chemical change because it involves a transformation that produces new substances with different properties. When concentrated nitric acid reacts with a copper penny, it results in the formation of copper nitrate and other products, both of which have different appearances from the initial penny. The observable color change and gas evolution suggest a chemical reaction has occurred.

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Reaction 3
Type of Change: Physical change
A physical change is characterized by a change in the state or appearance of a substance without altering its chemical composition. When water freezes, it transitions from a liquid to a solid state, but remains H2O. The visible evidence is the change from liquid to solid ice, which reflects a physical transformation rather than a chemical one.

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Reaction 4
Type of Change: Chemical change
I chose chemical change because the rotting apple undergoes a process that results in new chemical substances and different properties from the original apple. The decomposition leads to changes in color, texture, and odor, which are indications of chemical reactions breaking down the fruit. The visible signs of rot, such as browning and the appearance of mold, further confirm the occurrence of a chemical change.

Answer 2

In 1-2 sentences, describe why is it important to be able to identify between physical and chemical changes?

Answer 3

Identifying between physical and chemical changes is crucial because it helps us understand the nature of substances and their interactions, which is essential in fields like chemistry, materials science, and environmental science. Distinguishing these changes also informs practical applications, such as safety protocols in chemical reactions, preservation methods, and the recycling of materials.