Question

kinetic energy transfer quick check
when thermal energy is applied to water, the waters temperature rises until 100°c and then stays the same. which is the best explanation? (1 point)
○ when the water reaches 100°c, any increase in thermal energy becomes potential energy
○ when the water reaches 100°c, it can no longer absorb thermal energy
○ when the water reaches 100°c, the flow of thermal energy reverses, maintaining an equilibrium
○ when the water reaches 100°c, any increase in thermal energy goes to breaking the bonds between water molecules as the water boils and becomes steam.

Explanation:

When water reaches \(100^{\circ}C\) (boiling point at standard atmospheric pressure), it undergoes a phase change from liquid to gas (steam). During this phase change, the added thermal energy is used to break the intermolecular bonds (hydrogen bonds in water) rather than increasing the kinetic energy (which would raise the temperature). This is known as latent heat of vaporization.

• First option: Thermal energy during phase - change is not converted to potential energy in the way described. Potential energy in this context is related to intermolecular forces, and the energy is used for breaking bonds, not just a general “becomes potential energy” as stated.
• Second option: Water can still absorb thermal energy at \(100^{\circ}C\), but it is used for phase change, not for temperature increase.
• Third option: The flow of thermal energy does not reverse. Thermal energy still flows into the water (if the heat source is still on) for the phase - change process.

Answer:

When the water reaches \(100^{\circ}C\), any increase in thermal energy goes to breaking the bonds between water molecules as the water boils and becomes steam.