What are two examples of physical changes that occur in the world around us? Why are they physical changes?

Answer 1

Physical changes involve alterations in the form or appearance of a substance without changing its chemical composition. Here are two examples from the world around us:

1. Melting Ice: When ice is heated, it changes from solid to liquid water. This is a physical change because the ice (solid water) and the resulting liquid water are both H₂O, and no chemical bonds are broken or formed during the process. The change is reversible; if you freeze the water, it will turn back into ice.

2. Dissolving Sugar in Water: When sugar is added to water, it dissolves and forms a sugar solution. This is considered a physical change because the sugar molecules are dispersed in the water, but their chemical structure remains unchanged. The sugar can be recovered by evaporating the water, demonstrating that the process is reversible.

In both examples, the identity of the substances involved remains the same, which is a key characteristic of physical changes.

Answer 2

another example please

Answer 3

Sure! Here's another example of a physical change:

Boiling Water: When water is heated to its boiling point (100°C or 212°F at sea level), it changes from a liquid to a gas (steam). This process is a physical change because the water molecules remain as H₂O; the change is merely a transformation in the state of matter. The water can return to its liquid state when cooled down, making this change reversible.

Like the previous examples, boiling water involves a change in form (from liquid to gas) without altering the chemical composition of the substance involved.

Answer 4

another

Answer 5

Certainly! Here’s another example of a physical change:

Crushing a Can: When an aluminum can is crushed, its shape and appearance change dramatically, but the aluminum material itself remains unchanged at the molecular level. The can can be restored to its original form (although not perfectly) by applying pressure in the opposite direction, demonstrating that the change is reversible.

This is a physical change because the chemical properties of aluminum are not altered during the crushing process; only its physical form is modified.