Question

How many grams of phosphoric acid would be needed to neutralise 100g of magnesium hydroxide?

Answer 1

Hello Dear.

Here is the answer---

→→→→→→→→→

Reaction for the above Conditions will be ⇒

 3 Mg(OH)₂ + 2H₃PO₄ ---→  Mg₃(PO₄)₂ + 6H₂O

Molar Mass of Mg(OH)₂ = 58 grams/mole.
Mass of Mg(OH)₂ = 100 grams.
Molar Mass of H₃PO₄ = 98 grams/mole.


Now,
From the Equation,

 ∵ 3 × 58 grams of Mg(OH)₂ required to neutralize 2 x 98 grams of Phosphoric Acid.

∴ 1 grams------------------------------196/174 grams of Phosphoric acid.
∴ 100 grams---------------------------(196/174) × 100 grams of phosphoric acid.
                                       = 112.64 grams.


Thus, Mass of the Phosphoric acid required to Neutralize 100 grams of Magnesium Hydroxide is 1123.64 grams.


→→→→→→→→

Hope it helps.

Answer 2

Apply the formula to get the answer:

$(\frac{W}{E})H3PO4 = (\frac{W}{E}) Mg(OH)2$

W/98 x 3= 100/58 x 2

W = 112.0 gram