Question

Tetra phosphorus decaoxide combines with water to form phosphoric acid by the following unbalanced chemical equation:
$P_4{O}_{10}+H_{2}O\to H_{3}P{O}_4$
In order to form 105.0 g of phosphoric acid, how much tetraphosphorus decaoxide will you need?

• A. 262.6 g
• B. 138.1 g
• C. 75.97 g
• D. 72. 42 g

Answer 1

The correct option is C 75.97 g

Balanced chemical equation is:
$P_4{O}_{10}+6H_{2}O\to 4H_{3}P{O}_4$
Moles of phosphoric acid = $\frac{105}{98}=1.07$ mole
4 moles of $H_{3}P{O}_4$ are produced by 1 mole of $P_4{O}_{10}$
So, 1.07 mole of $H_{3}P{O}_4$ will be produced by $(\frac{1}{4}\times 1.07)$moles of $P_4{O}_{10}$
Mass of $P_4{O}_{10}$ required = $1.07\times \frac{1}{4}\times 284=75.97$ g