Constant Temperature with Added Heat

[Dahlia Kirov 3A]

Hi!

I had a question that relates to water's heating curve. I understand that at specific points for conversions from one phase to another (like a melting point for solid to liquid and a boiling point for liquid to gas), the temperature is said to remain constant even though heat is being added. I do not understand exactly why we are allowed to assume temperature is not being affected by the added heat.

[Megan Efhan 3A]

Hi! I believe it's because the added heat is being used as energy to facilitate a phase change and therefore the heat does not actually increase temperature.

[Michelle_Sen_3H]

The zeroth law of thermodynamics says that no heat is transferred between two objects in thermal equilibrium; therefore, they are the same temperature.

[dsmith1E]

The energy in the added heat is at work changing the phase of the compound – once the phase change is complete, then added heat increases the temperature.

[Sophia Spallone 1A]

When heat is added to a system to cause a phase change, that heat goes toward causing the phase change. It is my understanding that the heat will be used to cause the reactions that cause the phase change, so because it is used up, it does not stay and make the system warmer.