Which phase change is represented when a puddle of water disappears?
a
liquid to solid
b
liquid to gas
c
gas to liquid
d
solid to liquid
b. liquid to gas
The correct answer is b) liquid to gas.
The correct answer is (b) liquid to gas. When a puddle of water disappears, it undergoes a phase change known as evaporation, which is the transformation of a liquid into a gas. To understand this concept, we need to know about the different phases of matter and the conditions under which phase changes occur.
Phase changes occur when matter transitions between the three main phases: solid, liquid, and gas. When heat energy is added to a substance, its particles gain energy and move more rapidly, leading to a change in phase. Conversely, removing heat energy from a substance causes the particles to lose energy and slow down, resulting in a different phase change.
In the case of a puddle of water disappearing, the heat from the surroundings is absorbed by the liquid water. As the water molecules gain energy, they move faster and break free from the attractive forces holding them together. These individual water molecules then escape into the surrounding air as water vapor, which is the gas phase of water.
To further support our understanding, we can conduct an experiment. Take a small amount of water and place it in an open container. Leave it undisturbed for some time, and you will observe that the water gradually disappears. This is due to the process of evaporation, where the liquid water molecules on the surface gain enough energy to overcome the intermolecular forces between them and enter the gas phase as water vapor.
Therefore, when a puddle of water disappears, it represents the phase change of liquid to gas, or evaporation.