## pH of weak acid and its salt

Ashley McClearnen 1B
Posts: 59
Joined: Fri Sep 28, 2018 12:26 am

### pH of weak acid and its salt

In the example we did in lecture on Friday, why is the potassium not included in the equilibrium equation?

harshitasarambale4I
Posts: 58
Joined: Fri Sep 28, 2018 12:26 am

### Re: pH of weak acid and its salt

I believe it is not included when calculating K because it is a solid but I'm not sure as to why it isn't in the equation.

Rimsha Hussaini 1A
Posts: 31
Joined: Fri Sep 28, 2018 12:20 am

### Re: pH of weak acid and its salt

I believe Professor Lavelle mentioned that, if we wanted, we could include and write out the potassium as K+ on both sides of the equation. Nitrous acid stays as one molecule when in water, but potassium nitrite, as a salt, dissociates in water to form NO2- and K+. That NO2- is included in the HNO2 of the nitrous acid on the reactants side of the equation, but Lavelle chose not to include K+ in the equation because it does not play any part during this reaction as a whole. If you were to rewrite the equation including the potassium, it would look like the following.

$HNO_{2}^{-} +K^{+}+H_{2}O\rightleftharpoons H_{3}O^{+}+NO_{2}^{-}+K^{+}$

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