Which of the following is an example of only a physical change?
the creation of table salt
the smell of rotten eggs
the green color of the Statue of Liberty
dry ice becoming vapor
Dry ice becoming vapor is an example of only a physical change.
Dry ice becoming vapor is an example of only a physical change.
To determine which of the options is an example of only a physical change, we need to understand the difference between a physical change and a chemical change.
A physical change refers to a change in the physical properties of a substance without altering its chemical composition. On the other hand, a chemical change involves a reaction where substances are transformed into different substances with different chemical properties.
Let's evaluate each option:
1. The creation of table salt: This involves a chemical change, as table salt (sodium chloride) is formed by the combination of sodium and chlorine ions.
2. The smell of rotten eggs: This is a chemical change caused by the breakdown of sulfur compounds, producing hydrogen sulfide gas, which has a distinct rotten egg smell.
3. The green color of the Statue of Liberty: This is a physical change. The green patina on the Statue of Liberty's surface is due to the copper in the statue reacting with air and moisture over time to form copper carbonate. However, since the chemical composition of copper remains the same, this is considered a physical change.
4. Dry ice becoming vapor: This is a physical change known as sublimation. Dry ice, which is solid carbon dioxide, directly converts into gaseous carbon dioxide without entering a liquid phase.
Based on the explanations above, the example of only a physical change is "dry ice becoming vapor."