Question

What weights of P4O6 and P4O10 will be produced by the combustion of 31g of P4 in 32g of oxygen leaving no P4 and O2.

• A. 2.75g, 219.5g
• B. 27.5g, 35.5g
• C. 55g, 71g
• D. 17.5g, 190.5g

Answer 1

Answer: (B)

27.5g, 35.5g

Answer 2

(2)

P4 + O2 $\longrightarrow$ P4O6 + P4O10

31 gram 32 gram

According to question weight of P is conserved so

Let Mole of P4O6 = a

Mole of P4O10 = b

Initial weight of P = Final weight of P.

31 = [a × 4] × 31 + [b × 4] × 31

4 a + 4b = 1] (1) × 3

Initial weight of oxygen = Final weight of oxygen

32 = [ a × 6] × 16 + [a × 10] × 16

3a + 5b = 1] (2) × 4

12 a + 20 b = 4

12 a + 12 b = 3

So b = $\frac{1}{8}$ 8 b = 1

Similarly a =$\frac{1}{8}$

So weight of P4O6 = $\frac{1}{8}$ × 220 = 27.5 P4O10 $= \frac{284}{8} = 35.5$