## phase change

Sophia Dinh 1D
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### phase change

how can you tell if there has been a phase change?

Parker Smith
Posts: 102
Joined: Thu Jul 25, 2019 12:15 am

### Re: phase change

Usually the problem will tell you when a phase change occurs, or if on a phase diagram the temperature remains constant but enthalpy increases, the energy in crease was used for the phase change of the compound.

Sanjana Borle 2K
Posts: 111
Joined: Fri Aug 09, 2019 12:15 am

### Re: phase change

Like the diagram in class, you can tell that there is a phase change when the heat or enthalpy is increasing, but the temperature is not increasing, or delta T is zero.

KBELTRAMI_1E
Posts: 108
Joined: Sat Jul 20, 2019 12:17 am

### Re: phase change

Sanjana Borle 2K wrote:Like the diagram in class, you can tell that there is a phase change when the heat or enthalpy is increasing, but the temperature is not increasing, or delta T is zero.

Can the enthalpy increase AND the temperature remains the same while there still not being a phase change? Like I'm imagining the enthalpy of water at a positive value but without becoming a gas? Is that possible?

Posts: 81
Joined: Fri Sep 28, 2018 12:28 am

### Re: phase change

KBELTRAMI_1E wrote:
Sanjana Borle 2K wrote:Like the diagram in class, you can tell that there is a phase change when the heat or enthalpy is increasing, but the temperature is not increasing, or delta T is zero.

Can the enthalpy increase AND the temperature remains the same while there still not being a phase change? Like I'm imagining the enthalpy of water at a positive value but without becoming a gas? Is that possible?

I was wondering the same thing. Would any change in either of these, no matter to what degree, result in a phase change? Or is there an explicit threshold for each phase with regards to the reaction?

Julia Holsinger_1A
Posts: 50
Joined: Tue Feb 26, 2019 12:16 am

### Re: phase change

KBELTRAMI_1E wrote:
Sanjana Borle 2K wrote:Like the diagram in class, you can tell that there is a phase change when the heat or enthalpy is increasing, but the temperature is not increasing, or delta T is zero.

Can the enthalpy increase AND the temperature remains the same while there still not being a phase change? Like I'm imagining the enthalpy of water at a positive value but without becoming a gas? Is that possible?

I was wondering the same thing. Would any change in either of these, no matter to what degree, result in a phase change? Or is there an explicit threshold for each phase with regards to the reaction?

I believe because enthalpy is a state function there are explicit thresholds for each phase which is why, when plotted, it is a step diagram. That is how I understood it, there could be a different explanation

Posts: 81
Joined: Fri Sep 28, 2018 12:28 am

### Re: phase change

Julia Holsinger_1A wrote:
KBELTRAMI_1E wrote:
Can the enthalpy increase AND the temperature remains the same while there still not being a phase change? Like I'm imagining the enthalpy of water at a positive value but without becoming a gas? Is that possible?

I was wondering the same thing. Would any change in either of these, no matter to what degree, result in a phase change? Or is there an explicit threshold for each phase with regards to the reaction?

I believe because enthalpy is a state function there are explicit thresholds for each phase which is why, when plotted, it is a step diagram. That is how I understood it, there could be a different explanation

That is how I initially believed it to be. Are all diagrams for phase changes step diagrams?