The results obtained from the analyses of percentage by mass composition of chromium aqua chloride compounds A and B have the following cpercentage composition by mass ; Cr = 22.6, H2O = 31.2 and Cl =46.2. Compound A does not form precipitate with AgNO3 in aqueous solution while B does. I ) Determine the chemical formula the compounds of A and B showing clearly their
coordination sphere and giving reasons. [ Atomic masses in gram : H=1.0 , O=16.0
Cl =35.5 and Cr=52]
II ) Determine the primary and secondary valances of chromium in the two
compounds.
III) Determine the effective atomic number of Cr in A and B

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l