Consider the apparatus shown below, in which two 1.00-L bulbs are initially sepa
ID: 713030 • Letter: C
Question
Consider the apparatus shown below, in which two 1.00-L bulbs are initially separated from one another by a closed valve. One bulb is filled with 526 torr of sulfur dioxide and the other with 395 torr of oxygen, and the entire apparatus is at an initial temperature of 27°C Before mixing SO2 V=1.00 L P = 5.26 x 102 torr P = 3.95 x 102 torr T=27' C 02 V=1.00 L T=27"C The valve separating the bulbs is opened so that the gases mix, the entire container is heated, and the two gases react to produce the maximum possible amount of SO3. If the container is at a final temperature of 626 K when the reaction reaches completion, what is the total pressure? Pressure torrExplanation / Answer
2 SO2 (g) + O2 (g) -------------> 2 SO3 (g)
pressure of SO2 = 526 torr = 0.692 atm
moles of SO2 = 0.692 x 1 / 0.0821 x 300 = 0.0281 mol
moles of O2 = 0.5197 x 1 / 0.0821 x 300 = 0.0211 mol
2 SO2 (g) + O2 (g) -------------> 2 SO3 (g)
2 1 2
0.0281 0.0211
here limiting reagent is SO2 .
moles of O2 left = 0.0211 - (0.0281 / 2 ) = 0.00705 mol
pressure of O2 = 0.00705 x 0.0821 x 626 / 2 = 0.181 atm
= 137.69 torr
2 mol SO2 ---------------> 2 mol SO3
0.0281 mol --------------> ??
moles of SO3 = 0.0281 mol
P V = n R T
P x 2.00 = 0.0281 x 0.0821 x 626
P = 0.722 atm
pressure of SO3 = 548.8 torr
total pressure = 137.69 + 548.8 = 686.5
total pressure = 686 torr