Which of the following is an example of only a physical change?(1 point)
Responses
the smell of rotten eggs
the green color of the Statue of Liberty
the creation of table salt
dry ice becoming vapor
The option that is an example of only a physical change is:
"the green color of the Statue of Liberty"
This green color is due to the patina formed on the copper surface as a result of oxidation over time. It is essentially copper carbonate, which forms when copper oxidizes and results from exposure to moist air over a prolonged period. The underlying copper has not changed into a different substance, but rather its surface has undergone a physical reaction with the environment, changing the appearance but not the chemical composition of the copper.
what is the correct answer
Apologies for the confusion. The correct example of a physical change from the options provided is:
"dry ice becoming vapor"
This process is known as sublimation, where dry ice (solid carbon dioxide) changes directly from a solid to a gas without going through a liquid phase. This is strictly a physical change because the substance remains carbon dioxide before and after the change; its state of matter is what changes.
To determine which of the given options is an example of only a physical change, we need to understand what a physical change is.
A physical change refers to a transformation that alters the state or appearance of matter without changing its chemical composition. In other words, the substances involved in a physical change remain the same chemically, but their physical properties, such as shape, size, or state, may change.
Now let's examine each option to identify if it represents a physical change:
1. The smell of rotten eggs: This is not an example of a physical change because it involves a chemical reaction. Rotten eggs produce a foul smell due to the breakdown of molecules and the release of gases, indicating a chemical change.
2. The green color of the Statue of Liberty: The green color of the Statue of Liberty is caused by the oxidation of copper over time. This color change is also a result of a chemical reaction and is not solely a physical change.
3. The creation of table salt: The creation of table salt involves a chemical reaction called neutralization, where an acid and a base combine to form a salt and water. Therefore, this is not a physical change.
4. Dry ice becoming vapor: Dry ice, which is solid carbon dioxide (CO2), undergoes sublimation when it changes directly from a solid to a gas without becoming a liquid. This process is purely a physical change as it only involves a change in state. Therefore, dry ice becoming vapor is the correct example of a physical change from the given options.
In conclusion, the example of only a physical change among the given options is "dry ice becoming vapor."