Question

Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he placed the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation. Which statements correctly defend or dispute his conclusion? He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred. He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred. He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change. He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.

Answer 1

Explanation:

solids moving into solution is a physical change as the core structure of the molecules remain the same. evaporation of water and crystallization of salt are both physical changes as well.

The water does not change it's H2O chemical makeup because salt was dissolved into it.

Answer 2

The correct statement is- He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.

• A physical change is a change in which there is no formation of a new substance and it is usually reversible.
• Hence, addition of salt in water and evaporation of water both are physical changes as no new substance is formed. These are reversible changes as we can again obtain the salt after the evaporation of water.