To write ptcouncil.netical equations for water acting as an acid and as a base.

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Water (H2O) is an amazing compound in many respects. Here, us will think about its capability to behave as an acid or a base.

In some circumstances, a water molecule will accept a proton and thus act together a Brønsted-Lowry base. We saw an instance in the dissolve of HCl in H2O:

< mHCl + H_2O_(ℓ) ightarrow H_3O^+_(aq) + Cl^−_(aq) labelEq1>

In various other circumstances, a water molecule deserve to donate a proton and thus act as a Brønsted-Lowry acid. Because that example, in the presence of the amide ion (see instance 4 in section 10.2), a water molecule donates a proton, make ammonia as a product:

In this case, NH2− is a Brønsted-Lowry basic (the proton acceptor).

So, depending upon the circumstances, H2O can act as either a Brønsted-Lowry acid or a Brønsted-Lowry base. Water is no the just substance that deserve to react together an acid in some instances or a basic in others, yet it is absolutely the most usual example—and the most vital one. A substance that have the right to either donate or expropriate a proton, depending upon the circumstances, is referred to as an amphiprotic compound.

A water molecule have the right to act together an acid or a base even in a sample that pure water. Around 6 in every 100 million (6 in 108) water molecules experience the adhering to reaction:

This procedure is dubbed the autoionization that water (Figure (PageIndex1)) and occurs in every sample that water, even if it is it is pure or component of a solution. Autoionization occurs to some extent in any amphiprotic liquid. (For comparison, liquid ammonia experience autoionization together well, however only about 1 molecule in a million exchange rate (1 in 1015) reaction with an additional ammonia molecule.)

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Key Takeaway

Water molecules have the right to act as both an acid and a base, relying on the conditions.