Answer to Question #251336 in Molecular Physics | Thermodynamics for ellea

Question

2 C₂H_6(g) +7 O_2(g) = 4 CO_2(g) + 6 H₂O_(g)

1. Calculate the volume in liters of CO₂ at STP, that could be produced from 7.25 g C₂H₆.

2. Calculate the volume of O₂ at 100^oC and 1.25 atm, that would react with 7.52g of C₂H₆

Answer 1

1. M(C₂H₆) = 30.07 g/mol

n(C₂H₆) $= \frac{7.25}{30.07} = 0.241 \;mol$

According to the reaction equation

n(CO₂) = 2n(C₂H₆) $= 2 \times 0.241 = 0.482 \;mol$

At STP one mole of any gas occupies 22.4 L.

V(CO₂) $= 22.4 \times 0.482 = 10.80 \;L$

2. n(C₂H₆) $= \frac{7.52}{30.07} = 0.25 \;mol$

According to the reaction equation

n(O₂) $= \frac{7}{2}$ n(C₂H₆) $= \frac{7}{2} \times 0.25 = 0.875 \;mol$

Ideal gas law:

$pV=nRT \\ p = 1.25 \;atm \\ T = 100 +273 = 373 \;K$

R = 0.08206 L×atm/mol×K

$V(O_2) = \frac{nRT}{p} \\ = \frac{0.875 \times 0.08206 \times 373}{1.25} \\ = 21.42 \;L$