Question

Formula of phosphoric acid is $H_{3}P{O}_4$? A metal M forms chloride of the formula $MC{l}_2$. What is the formula of its phosphate?

Answer 1

Chemical formula is determined as follows

• Write symbol of elements.
• Below that write valency of the elements.
• Cross multiply valency & elements.

Example:- (Refer to Image)

• Metal forms chloride of the formula $MC{l}_2$. According to rule of chemical formula valencies are cross multiplied with elements. Hence, valency of $M$ is $2$.
• As $M$ has valency $2$, it combines with $HP{O}_4^{-2}$ to form $MHP{O}_4$.