Heating Curve Phase Changes

[805312064]

Why is the heating curve flat when changing phases of a substance?

[Megan Cao 1I]

it's flat because it's the substance changing phases. the slope is zero so there's no temperature change, but there's a physical state change for the substance

[Subashni Rajiv 1K]

It is where the state is changing. It can be either the solid/liquid in between phase or the liquid/gas in between phase.

[Jessica Katzman 4F]

The substance can change phases at a constant temperature. This is why ice can melt into water at room temperature, and if you check on the ice at different times you will see the ratio of ice to water change.

[Shrayes Raman]

It is flat because the addition of energy as heat into the system causes the substance to fully change phases before increasing the temperature of the substance.

[Cooper Baddley 1F]

It's flat when the energy in changes from being used to heat the substance to changing the phase of the substance

[haileyramsey-1c]

The flat line represents the phase change and the vertical/slanted line represents the heating (enthalpy increase).

[Amanda Mei 1B]

Temperature doesn't change during a phase change. Heat added to a substance either raises the temperature or causes a phase change, but not both simultaneously. If a solid is heated at its melting point, its temperature remains the same until it has completely melted because melting requires energy. After the solid melts, heating the liquid raises its temperature and the slope is no longer a flat line, until the boiling point is reached.

[Manav Govil 1B]

I believe that the heat energy inputted into the system at that time is there to break or form the bonds, transitioning the state of the sample.

[Alexandra Bartolome 2H]

The heat supplied to cause a substance's phase change does not actually change the heat of the substance.

[305385703]

During the flat part of a phase diagram, all the heat is being used to separate the molecules and thus change the phase. There is no heat being contributed to the random motion of the particles and thus the temperature remains constant.

[Callum Guo 1H]

It takes energy to change a phase from one to another. For example, if you're heating Ice into liquid water, it'll take a certain amount of energy to get it from a solid to a liquid. This is the reason why steam at 100 degrees Celsius causes harsher burns than liquid water at 100 degrees Celsius (because the steam has more energy)