A container with a volume of 20.0 L holds N₂(g) and H₂O(l) at 300 K. The pressure is found to be 1.0 atm. The water is then split into hydrogen and oxygen by electrolysis. After the reaction is comple

Question

A container with a volume of 20.0 L holds N₂(g) and H₂O(l) at 300 K. The pressure is found to be 1.0 atm. The water is then split into hydrogen and oxygen by electrolysis. After the reaction is complete, the pressure is 1.56 atm. What mass (in g) of water was present initially in the container? The aqueous tension of water at 300 K is 0.04 atm. (R = 0.08 L-atm/K-mol)

TestHub · Accepted Answer

Initially P(N₂) = 1.0 - 0.04 = 0.96 atm. After complete electrolysis no liquid water remains, so no aqueous tension; gases are N₂, H₂ (w mol) and O₂ (w/2 mol).

1.56 = 0.96 + 1.5w x (0.08 × 300/20.0) ⇒ 1.5w x 1.2 = 0.60 ⇒ 1.5w = 0.50 ⇒ w = 1/3 mol.

Mass of water = (1/3) × 18 = 6 g.

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