a. 2PH3 + 4O2 → P2O5 + 3H2O
b. M(PH3) = 40 g/mol
M(O2) = 32 g/mol
"n = \\frac{m}{M}"
n(PH3) = 35/40 = 0.875 mole
n(O2) = 2n(PH3) "= 2\\times 0.875 = 1.75 \\;mol"
"m = n\\times M"
m(O2) "= 1.75 \\times 32 = 56\\; g"
c. M(P2O5) = 284 g/mol
m(H2O) = 18 g/mol
n(P2O5) = 1/2n(PH3) "= 1\/2\\times 0.875 = 0.4375\\; mol"
m(P2O5) = "0.4375 \\times 284 = 124.25\\; g"
n(H2O) = 3n(P2O5) "= 3\\times 0.4375 = 1.315\\; mol"
m(H2O) "= 1.315 \\times 18 = 23.67 \\;g"
d. Proportion:
250 g — 64 %
x — 100 %
x = 391 g
n(P2O5) "= \\frac{91}{284} = 1.37 \\;mol"
n(PH3) = 2n(P2O5) "= 2 \\times 1.37 = 2.74 \\;mol"
m(PH3) "= 2.74 \\times 40 = 109.6 \\;g"
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