Question

The formula of chloride of a metal $ M $ is $ MC{l_3} $ , then the formula of phosphate of metal $ M $ will be:
(A) $ MP{O_4} $
(B) $ {M_2}P{O_4} $
(C) $ {M_3}P{O_4} $
(D) $ {M_2}{(P{O_4})_3} $

Answer 1

Hint: Here we need to analyse the chloride formula of the metal which is overall trivalent but it is important to note here that the chlorine is monovalent and as we know that phosphate is trivalent and in order to main electrical neutrality the formula will be so derived.

Complete step by step solution:
Firstly we should know here that the valency of chlorine is $ - 1 $ hence we can say here that the valency of the compound is $ + 3 $ . Further the valency of the phosphate ion is $ P{O_4}^{3 - } $ further we can conclude here that by the cross multiplication method we can derive the formula of phosphate with the metal ion and cross multiplying we get the formula as $ MP{O_4}^{} $ as the valency here of both is same and they further combine in unit ratio. Also we can say that the formula derived is this because the chlorine of a metal is trivalent and therefore that of the phosphate will also be trivalent and further they will combine to give the required formula in order to maintain the electrical neutrality. So, depending on the formula of the chloride of the metal we can further derive the formula of the phosphate of the metal.
Hence we can say that option A is the correct formula for the question asked.

Note:
We should note here that the metal phosphates are demonstrated to be hydraulically thermal stable and further it is interesting to note here that they are further able to exhibit good conductivity at the elevated temperatures.