$Keq=\ \lceil H2O\rceil$  

 $Keq\ =\ \frac{\lceil H2O\rceil}{\lceil H2O\rceil}$  

 $Keq\ =\frac{1}{\lceil H2O\rceil}$  

 $Keq\ =\ \lceil H2O^{ }\rceil^2$