Amphiprotic (1 Viewer)

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Shouldn't there be only single arrows as it is a neutralisation reaction which goes to completion?

 

[wizzkids]

No.
The amount of OH^- and H₃O⁺ ions present is very small, approximately 10^-7 M.L^-1. These equations are describing how the pH of water will be altered by the presence of this ion (not by much it would seem, because this ion is amphiprotic)
These equations are describing equilibrium.

 

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ohhh right ic but how do you know the amounts of OH- and H3O are small tho?

 

[wizzkids]

ohhh right ic but how do you know the amounts of OH- and H3O are small tho?

Good question. This ion has the ability to be both a proton donor and a proton acceptor. That tells us something about how this ion is going to behave in water. If you try to lower the pH of the solution by adding more H₃O⁺, it will react with them, and if you try to raise the pH of the solution by adding OH^- it will react with them too. So the pH can't move very far away from neutral which is 7 or -log[H⁺], and we know that from the K_a of water. That is how we can deduce that the concentrations of H₃O⁺ and OH^- must be small.

 

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ohhhh ic tysm