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.
A water molecule, because of its shape, is a polar molecule. That is, it has one side that is positively charged and one side that is negatively charged. The molecule is made up of two hydrogen atoms and one oxygen atom. The bonds between the atoms are called covalent bonds, because the atoms share electrons.
HCl = H⁺ + Cl⁻
c(HCl)=9.8*10⁻⁵ mol/l
pH=-lg[H⁺]
[H⁺]=c(HCl)
pH=-lg{c(HCl)}
pH=-lg{9.8*10⁻⁵}=4.009
pH=4.009
