Answer to Question #170485 in General Chemistry for Surendra

Question

A mixture containing only CS₂(g) and excess O₂(g) at a total pressure of 90 kPa is placed in a sealed vessel. A spark causes the CS2 to ignite, burning it completely, according to the equation: CS2(g)+3O2(g)→CO2(g)+2SO2(g) After the reaction is completed and the vessel is cooled to the initial temperature, the total pressure in the vessel drops to 80 kPa. What was the mole fraction of O₂(g) in the initial mixture?

Answer 1

Here, we can liken the pressure to mole

We would notice that the pressure for oxygen = (90-80)kPa = 10kPa

We can say the fraction of oxygen = 10/90 = 1:9