Gas A and gas B are combined in a flask at initial pressures of 1.0 atm each. The flask is sealed and over time they react to completion to give gas C according to the following chemical equation: 2A(g) + B(g) $\rarr$ C(g)
Assuming the temperature stays constant, what will be the total pressure in the flask after the reaction goes to completion
A) 0.33 atm
B) 0.50 atm
C) 0.67 atm
D) 0.75 atm
E) 1.0 atm

Question

Quizplus · Accepted Answer

Given the stoichiometry of the reaction, 2 moles of A react with 1 mole of B to produce 1 mole of C. Starting with 1 atm pressure each for A and B, the limiting reactant is A because it requires twice as much A as B for the reaction. After the reaction, all of A will be consumed, and 0.5 atm of B will remain (since half of B reacts). The reaction produces 0.5 atm of C (since 1 atm of A produces 0.5 atm of C). The total pressure is the sum of the pressures of B and C, which is 0.5 atm + 0.5 atm = 1.0 atm. The temperature is constant, and the volume doesn't change, so the total pressure remains the same as the initial total pressure.

Gas a and Gas B Are Combined in a Flask →\rarr→

Gas a and Gas B Are Combined in a Flask $\rarr$