Heating curve

[Shane_Yu_3K]

Hello,

Can anyone explain why the temperature stays the same when water goes through melting or vaporization?

Thank you!

[Julie Tran 3C]

Hello,

As a phase change occurs, heat energy being added to the substance is contributed towards breaking bonds (which would lead to a change like melting or vaporization) rather than increasing the motion of the substance's molecules (which would increase temperature). Thus, even though there is a change in the amount of heat energy (enthalpy) the system has, the temperature still stays constant.

Hope this helps!

[Ryan Blaydon 1K]

It is not because bonds are being broken but rather the intermolecular forces are being broken or weakened. In the case of water, it is basically the hydrogen bonding (IMF) that is being broken. The energy goes to this rather than the temperature. I hope this helps!

[Julie Mai 1K]

Hello!

The temperature of water stays the same through melting or vaporization because there's a phase change happening. With a phase change, the energy goes towards breaking intermolecular forces instead of changing the temperature. Hope this helped!

[Michelle Li 2B]

Hi! When water goes through melting or vaporization, it is experiencing a phase change. Therefore, the temperature doesn't change since the energy is put into breaking the IMFs in the water molecules in order to convert them to a different state (liquid or gas). When the temperature does change, the energy is put into increasing the motion of the particles, which would make the temperature increase.

[gracebinder3I]

Hi!
Melting and vaporization are phase changes where heat is required. This heat is used to break bonds to change state, not the kinetic energy between molecules (which will change the temperature). So, the temperature of the sample remains constant even though heat is being supplied.
I hope this helps!

[Amy Huang]

Hi! Heat is required during phase changes (solid to liquid or liquid to gas). Thus as heat is provided continuously, they are used to support phase change and therefore cannot continue to increase the temperature.

[A 3F]

Heat is required in order to have a phase transition of either melting or vaporization. The reason why the temperature doesn't increase is because the heat is being used to break the intermolecular forces between the molecules rather than increasing the kinetic energy, which will increase the temperature.

[HemangD 3K]

Temperature only increases when kinetic energy or the motion of particles increases. During a phase change, the heat supplied isn't being used to increase kinetic energy. Rather, it's being used to break hydrogen bonds (the breaking of hydrogen bonds is what allows phase change to occur). This is why temperature remains constant during melting or vaporization.

[Nicole Weinstein 3E]

Heat is required for this phase change, so the energy is being put into breaking bonds of intermolecular forces rather than raising the temperature. That is why it remains relatively constant during this process.

[Om Patel]

the temperature stays the same because it is the energy that is being added in the phase change

[Anubhav_Chandla1G]

Temperature does not increase since the increased energy through heat is breaking the bonds for a phase change, leading temperature to stay constant.

[Sabira Mohammed 3I]

Hi, when melting or vaporization occurs, the energy from the heat added is being used to break intermolecular forces between water molecules so the phase change can occur, so temperature doesn't increase during that time.

[Russell Chuang 1J]

The reason why temperature stays the same during heating in vaporization or melting is because that extra energy of heat is used to break the bonds between the molecules.

[Charlie Sjogren-Black]

The temperature stays the same because the energy is being used to break bonds within the molecules and transfer to the next phase.

[Sarah Hong 2K]

You know a phase change occurs when the temperature of the sample remains constant even when heat is being applied because the heat is going to intermolecular forces breaking rather than increasing the temperature.

[Samir Panwar]

The temperature stays the same during the melting and vaporizing process because the energy is used in the breaking of the bonds between molecules before the transfer phase.

[Kimberly_martinez2I]

Hello,
Temperature stays constant because the energy is used to break the bonds rather than increasing the temperature of the system.

[Maham Kazmi 2J]

Hey! The temperature stays the same during a phase change because the heat is being used to break bonds (such as Hydrogen bonds when converting H2O liquid to gas) rather than being used for thermal motion. An increase of thermal motion is actually what results in a temperature increase during a "non phase change"!

[Benjamin Nguyen 1J]

Since the water is changing phases, the energy absorbed is being used to break intermolecular forces instead of increasing the kinetic energy of the particles.

[Isabelle Kim 3E]

The heating curve for water has two specific phase transitions, which you've mentioned. These two phase transitions are shown at the plateaus on the heating curve, whereas the other parts show a change in temperature (increasing/decreasing). At these plateaus, you can observe how temperature does not change since there is heat energy being absorbed/released during the phase transitioning chemical reactions. The x-axis measures the heat and y-axis measures the temperature. I find it helpful to understand the graph fully in order to get a better sense of the concept.
Hope I kind of clarified your question!

[Ashley Wilson 2L]

When a substance is changing from a solid to a liquid, the molecules are changing from being in rigid positions to moving or rolling around each other. Therefore, the intermolecular forces between the molecules must be weakened. The energy or heat that is applied to the solid is used solely to weaken the intermolecular forces, and not to increase the average kinetic energy of the molecules. Because of this, the temperature of the molecules does not change while the amount of heat does change.

[Ivy Vo Dis 1C]

When heat is added during the process of melting or vaporization, this heat energy is going toward breaking bonds. By breaking these bonds, a phase change can occur (from solid to liquid or from liquid to gas). Meanwhile, when heat is added to a liquid, prior to the vaporization curve, the liquid's temperature will increase. Because energy is going into breaking bonds, the temperature of the vapor/water/ice will not increase.

[405479701]

A phase change does not change the temperature because the energy is going to the intermolecular forces being broken or weakened.

[Helen Ringley 2E]

This is a great question! When a substance is not going through a phase change (like water at room temperature) any heat that is added will correlate to an increase in temperature. However, when a substance reaches the threshold of a phase change, that phase change requires energy. This means that now, if you add heat, instead of affecting the temperature all this energy will go towards the phase change. This means that there is no change in the temperature but the liquid would become a gas.
Hope that makes sense!

[SerenaSabedra]

When you add heat to the water and it undergoes a phase change, that heat energy is absorbed and put towards breaking the bonds instead actually increasing the motion of molecules, so the actual temperature of the system does not rise.

[Katherine Li 1A]

This is because the energy being applied to the system goes into changing the phase of the water, instead of raising the temperature. It is only after the phase change has been completed that energy going into the system will change its temperature.

[Talia Tam 3L]

During a phase change, the energy added will go into breaking bonds instead of continuing to raise the temperature.

[Caitlin Gee 2K]

The heat energy being added is going into the phase change, rather than heat.

[JasmineReyes-2K]

Hi!,
This is because the heat energy is what is going through the phase change, not the heat

[Achyutha Kodavatikanti_3H]

temperature stays the same during phase changes because all the heat being transferred is used to break/form the bonds rather than heating/cooling.

[Natalie Coughlin 1I]

Temperature stays the same as the heat is going towards breaking the bonds for a phase change, rather than raising the temp.

[Nicole Ton 3C]

During a phase change, the heat that is going into a system is being used to break apart bonds rather than increase the temperature. This is why the temperature stays the same when water goes through melting or vaporization, which is a phase change.

[Acharya Ranawat 3E]

In the heating curve. Whenever the temperature is rising, molecules are moving faster. At the flat points on the curve, IMFs are being broken which cause for the temperature to stay the same.

[Amanda Dankberg 1B]

It is flat because the heat being added to the system is going towards breaking bonds rather than changing the temperature

[005502505]

Hello; the line in a phase change diagram remains flat during a change of state b/c the heat energy is going into breaking the bonds to result in a phase change (ex: solid -> liquid). The line should be increasing (positive slope) leading up to / after the phase change. Hope this helps!!

[Isela Tamayo 3H]

it stays the phase because there is a phase change

[605607825]

Hello!

From my understanding, the temperature stays the same when water goes through melting because heat is being added to break the intermolecular forces during melting. For example, when ice is being melted, heat is used to turn the ice into water. There is no increase of kinetic energy so the temperature will remain the same. During vaporization the heat energy being supplied is utilized to alter the phase of matter. Heat will be used to turn the boiling water into vapor. Although the temperature remains constant, the enthalpy will change in the system. I hope this helps!