Spontaneous Reaction






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Semi Yoon
Posts: 60
Joined: Fri Sep 28, 2018 12:27 am

Spontaneous Reaction

Postby Semi Yoon » Sun Mar 10, 2019 11:56 pm

Why would the precipitation of snowflakes inside a cloud at -10C and 0.839 atm be a spontaneous reaction?

GavinAleshire1L
Posts: 29
Joined: Fri Sep 28, 2018 12:21 am

Re: Spontaneous Reaction

Postby GavinAleshire1L » Mon Mar 11, 2019 12:35 am

I was confused by the same question. How do we interpret delta G without knowing the magnitude of delta H and T delta? Is there a way to use pressure to help solve?

Cole Doolittle 2K
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Joined: Fri Sep 28, 2018 12:20 am

Re: Spontaneous Reaction

Postby Cole Doolittle 2K » Mon Mar 11, 2019 12:41 am

I am also confused. I understand that delta H would be negative if you are freezing and thus losing heat, but wouldn't delta S also be negative if you are losing entropy going from a liquid to a solid? Thanks in advance!

Pritish Patil 1K
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Joined: Fri Sep 28, 2018 12:24 am

Re: Spontaneous Reaction

Postby Pritish Patil 1K » Tue Mar 12, 2019 1:28 pm

I'm not completely sure. But I assumed that because it is precipitation, the water is going from liquid to solid state. Because the freezing point of liquid water was 0 degrees C, I assumed that the precipitation would be spontaneous as the surrounding temperature was -10 degrees C, which is less than the freezing point.

Noah Fox 1E
Posts: 31
Joined: Fri Sep 28, 2018 12:20 am

Re: Spontaneous Reaction

Postby Noah Fox 1E » Tue Mar 12, 2019 11:06 pm

I don't think this is the way to answer the question but something that helps me conceptualize it is that heat diffuses out. If a sample of water is in a 10 degree Celsius space, heat leaves the sample and the bonds form spontaneously because of the conditions it is in.

yuetao4k
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Re: Spontaneous Reaction

Postby yuetao4k » Fri Mar 15, 2019 6:23 pm

I thought of it as a spontaneous reaction because when the temperature is -10 degrees C, then snow precipitating is spontaneous, thus delta G is negative.


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