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Offline Win,odd Dhamnekar

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Coupled equilibria question
« on: January 08, 2021, 12:02:18 PM »
 A 0.125-M solution of Mn(NO3)2 is saturated with H2S([H2S]=0.10 M). At what pH, does MnS begin to precipitate?

MnS(s) ::equil:: Mn2+ (aq) + S2- (aq) Ksp= 4.3 × 10-22

H2S (aq) + 2H2O (l)  ::equil:: 2H3O+ (aq) + S2- (aq) K=1.0× 10-26

  I am now studying coupled equilibria chapter to answer this question.  Your guidance would be helpful.
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Offline Win,odd Dhamnekar

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Re: Coupled equilibria question
« Reply #2 on: January 11, 2021, 03:37:58 AM »
 I found the answer to this question on the other chemistry educational website on internet, but i don't understand the meaning of highlighted area. What is K1 K2 (H2S)?

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Offline mjc123

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Re: Coupled equilibria question
« Reply #3 on: January 11, 2021, 05:38:54 AM »
K1 and K2 are the two ionisation constants of H2S:
H2S + H2::equil:: H3O+ + HS- K = K1
HS- + H2::equil:: H3O+ + S2-  K = K2

Offline Win,odd Dhamnekar

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Re: Coupled equilibria question
« Reply #4 on: January 11, 2021, 09:44:09 AM »
 Thanks.
Any science consists of the following process.
 1) See 2) Hear 3) Smell if needed 4) Taste if needed
5) Think 6) Understand 7) Inference 8) take decision [Believe or disbelieve, useful or useless, healthy or unhealthy, cause or effect, favorable or unfavorable, practical or theoretical, practically possible or practically impossible, true or false or  any other required criteria]

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