Consider the following reaction in a closed reaction flask. If 0.600 atm of gas A is allowed to react with 1.20 atm of gas B and the reaction goes to completion at constant temperature and volume, what is the total pressure in the reaction flask at the end of the reaction? What are the partial pressures of the gases in the flask?
A(g) + 3B(g) → AB3(g)
What's the limiting reagent? See discussion below.
...........A + 3B ==> AB3
initial..0.6...1.2.....0
change..-0.4..-1.2....+0.4
equil....0.2....0.....0.4
0.6 atm A will form 0.6 atm AB3 but
1.2 atm B will form 1.2 x (1/3) = 0.4 atm AB3; therefore, B is the limiting reagent.
Total pressure is 0.2 + 0.4 = ? atm and partial pressures are given in the equilibrium line.
You can work this by assuming some T and some V, solve for moles and work it with moles. Then use PV = nRT and solve for pressures of each but it takes much longer. I get the same answer either way.
To determine the total pressure in the reaction flask at the end of the reaction, we need to consider the stoichiometry of the reaction.
From the balanced equation, we see that 1 mole of A reacts with 3 moles of B to form 1 mole of AB3.
Since the reaction goes to completion, all of A and B will react to form AB3. Therefore, we can assume that all of A will be consumed.
To calculate the total pressure at the end of the reaction, we need to consider the partial pressure of AB3 as well as the partial pressures of A and B.
Using the ideal gas law, we can relate the number of moles, volume, and pressure of a gas:
PV = nRT
where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
Since the reaction is taking place in a closed reaction flask with constant volume and temperature, the total pressure at the end will be the sum of the partial pressures of the gases (P_total = P_A + P_B + P_AB3).
Let's assume 1 mole of A and 3 moles of B initially in the flask. The total moles of gas at the beginning is 1 + 3 = 4.
Using the ideal gas law, we can calculate the initial partial pressures of A and B:
P_A = (n_A / n_total) * P_total
P_B = (n_B / n_total) * P_total
where n_A and n_B are the number of moles of A and B, respectively, n_total = n_A + n_B is the total number of moles of gas in the flask, and P_total is the total pressure at the end of the reaction.
Since we assume all of A reacts, the moles of A at the end is 0. Therefore, the moles of B and AB3 at the end of the reaction will be 3 and 1, respectively.
Now, we can calculate the partial pressures of B and AB3 at the end:
P_B = (3 / 4) * P_total
P_AB3 = (1 / 4) * P_total
To find the total pressure at the end of the reaction, we add the partial pressures:
P_total = P_A + P_B + P_AB3
= 0 atm + (3 / 4) * P_total + (1 / 4) * P_total
= (3/4 + 1/4) * P_total
= (4 / 4) * P_total
= P_total
Thus, the total pressure in the reaction flask at the end of the reaction is the same as the partial pressures of each gas.
At the end of the reaction, the total pressure in the flask will be 0.600 atm + 1.20 atm + 0 atm = 1.80 atm.
The partial pressures of A, B, and AB3 in the flask will be 0.600 atm, 1.20 atm, and 0 atm, respectively.
To find the total pressure in the reaction flask at the end of the reaction, we need to determine the partial pressures of gases A, B, and AB3.
First, we need to determine the stoichiometry of the reaction. From the balanced equation:
1 mole of A reacts with 3 moles of B to produce 1 mole of AB3.
Let's assume we have x moles of A and y moles of B initially. After the reaction goes to completion, all of gas A will react, so the moles of A remaining will be 0. Since 1 mole of A reacts with 3 moles of B, we can say that 3x moles of B are required for the complete reaction. Therefore, the moles of B remaining after the reaction will be y - 3x.
Now, let's use Dalton's law of partial pressures to determine the partial pressures of gases A, B, and AB3. According to this law, the total pressure is the sum of the partial pressures exerted by each gas.
Partial pressure of gas A (PA) = moles of A remaining (0) * pressure of A (0.600 atm) / total moles of gas remaining (0+x+(y-3x))
Partial pressure of gas B (PB) = moles of B remaining (y-3x) * pressure of B (1.20 atm) / total moles of gas remaining (0+x+(y-3x))
Partial pressure of gas AB3 (PAB3) = moles of AB3 produced (x) * total pressure at the end of the reaction / total moles of gas remaining (0+x+(y-3x))
Since the reaction goes to completion, all the gas A reacts and converts to gas AB3. Therefore, the total moles of gas remaining will be x + (y-3x).
The total pressure in the reaction flask at the end of the reaction will be equal to the sum of the partial pressures:
Total pressure = PA + PB + PAB3
Substituting the values into the equations, you can calculate the partial pressures and the total pressure in the reaction flask at the end of the reaction.