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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: xshadow on October 07, 2019, 05:29:12 AM

Title: H2O vs H2S basicity
Post by: xshadow on October 07, 2019, 05:29:12 AM
HI..I have some doubt about the relative basicity order of H2O and H2S


If H2O and H2S act as a base I'll get:

H3O+
H3S+

Now I think that H3S+ is more stable than H30+ because the positive charge is disperded in a bigger volume

So H3S+ is more stable...so H2S  is more reactive than H2O in adding a proton ,H+ ---> H2S is a better  base


But is this correct?  Because in water H2S never adds a proton while H2O can. But  consdering the basicity in gas phase ...maybe...?
Thanks
Title: Re: H2O vs H2S basicity
Post by: ... on October 07, 2019, 06:05:21 AM
Quote
[...]H2S is a better  base
Incorrect. Think about it again...
Title: Re: H2O vs H2S basicity
Post by: xshadow on October 07, 2019, 06:14:21 AM
Quote from: fleckenforscher on October 07, 2019, 06:05:21 AM
Quote
[...]H2S is a better  base
Incorrect. Think about it again...
I'll  try  :
H2S vs H2O basicity:

I have to see which lone pore is more ""basic"", more avaiable??

For two different elements of a group the main difference is the size:

S is bigger than O...so O has a bigger electron density...better base?

Now is it correct?



BUT (a big but) if I think at H3O+ vs H3S+ stabilty I can say that H3S+ is more stable because the positive charge is dispersed on a bigger volume...H3S+ is more stable...so H2S is more reactive than H2O in order to form H3S+ (than H3O+ to form H2O)

In other words why is H3S+  less stable than H3O+??
Because this is the requirement in order to have H2O basicity(reactivity towards H3O+ formation  ) > H2S basicity(reactivity towards H3S+ formation)


Thx