Final answer:
To determine the pressure in the flask after the reaction, one must consider the stoichiometry of the reaction between SO₂ and O₂ to form SO₃, which consumes SO₂ in a 2:1 ratio. The remaining moles of gas are used in the Ideal Gas Law formula to calculate the pressure at the given temperature and volume.
Step-by-step explanation:
To answer the question regarding the pressure in the flask after the reaction between SO₂ and O₂ is complete, we need to apply principles of chemical equilibrium and the Ideal Gas Law. The balanced chemical equation for the formation of SO₃ is:
2 SO₂(g) + O₂(g) ⇒ 2 SO₃(g)
Since we have equal moles of SO₂ and O₂, and the reaction consumes SO₂ and O₂ in a 2:1 ratio, the limiting reactant here is SO₂. After the reaction, if we assume that all the SO₂ reacts, we'll have 0.20 mol of SO₃ formed and no SO₂ left. The initial amount of O₂ is 0.20 mol, and the reaction consumes half of that, leaving 0.10 mol of O₂ unreacted.
The total number of moles of gas after the reaction is the sum of moles of SO₃ and unreacted O₂, which is 0.20 mol + 0.10 mol = 0.30 mol. To find the pressure, we can use Ideal Gas Law:
PV = nRT
Where:
P is the pressure
V is the volume (4.0 L)
n is the number of moles of gas (0.30 mol)
R is the ideal gas constant (0.0821 L·atm/(K·mol))
T is the temperature in Kelvin (25ºC + 273 = 298 K)
Substitute the known values into the Ideal Gas Law equation and solve for P:
P = (nRT)/V
P = [(0.30 mol)(0.0821 L·atm/(K·mol))(298 K)] / (4.0 L)
Calculate P to get the pressure in the flask after the reaction is complete.