9. How Does AuCl3 React With Water?

AuCl3, also known as gold(III) chloride, reacts with water to produce hydrochloric acid (HCl) and auric acid (HAuO4).

The balanced chemical equation for this reaction is:

AuCl3 + 3H2O → H[Au(OH)4] + 3HCl

In the reaction, one molecule of AuCl3 combines with three molecules of water. The AuCl3 molecule donates its three chlorine atoms to form three molecules of HCl, while the remaining Au atom coordinates with four oxygen atoms from water molecules to form one molecule of auric acid (HAuO4). The resulting solution will be acidic due to the presence of HCl.

This reaction can also be written using the Lewis acid-base theory, where AuCl3 acts as a Lewis acid (electron pair acceptor) and water acts as a Lewis base (electron pair donor). The reaction proceeds through the coordination of water molecules to the Au atom, followed by the donation of electron pairs from the oxygen atoms to the Au atom, forming the complex ion [Au(H2O)4]3+.

Overall, the reaction between AuCl3 and water is an important step in the preparation of gold nanoparticles and other gold-containing compounds in aqueous solution.