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
`3 Mg (OH)_(2) + 2H_(3) PO_(4) rarr Mg(PO_(4))_(2) + 3H_(2) O`
`(3 xx 58.3)/(2 xx 98) = (100)/(W), :. W = 112 g`