Water is constantly being cycled between the atmosphere, the ocean and land. This cycling is a very important process that helps sustain life on Earth. As the water evaporates, vapors rise, and condense into clouds. The clouds move over land, and precipitation falls in the form of rain, ice, or snow.
In the reaction,
Cr3+(aq) + 6H2O -------> [Cr(H2O)6]3+(aq)
Cr3+ IS THE LEWIS ACID H2O is the Lewis base.
A Lewis acid is a compound or chemical that accepts a lone pair of electrons. In the above equation, Cr3+ is accepting the lone pair of electrons.