Question

How many grams of phosphoric acid would be needed to neutralise `100 g` of magnesium hydroxide? (The molecular weight are: `H_(3)PO_(4) = 98` and `Mg(OH)_(2) = 58.3)`
A. `66.7 g`
B. `252 g`
C. `112 g`
D. `168 g`

Answer 1

Correct Answer - C
Meq. of `H_(3)PO_(4)=`Meq. of `Mg(OH)_(2)`
`:.` Meq. of `Mg(OH)_(2)=(100)/(58.3//2)xx100`
`=3430.53`
`(H_(3)P_(4)`is tribasic acid)
`:. (w)/(98//3)xx1000=3430.53`
`:. w=112g`