Ammonium iodide dissociates reversibly to ammonia and hydrogen iodide:
NH4I(s) ↔ NH3(g) + HI(g)
At 400ºC, Kp = 0.215. If 150 g of ammonium iodide is placed into a 3.00-L vessel and heated to 400ºC, calculate the partial pressure of ammonia when equilibrium is reached
help plz.. atleast set me up so i know where to go or how to solve
NH4I(s) ==> NH3(s) + HI(g)
Kp = PNH3*PHI = 0.215
mole fraction NH3 = 0.5
mole fraction HI = 0.5
(Since moles NH3 = moles HI at equilibrium, then each will be just 1/2 of the total which makes mole fraction of each 0.5.)
PNH3 = XNH3*Ptotal = 0.5*Ptotal
PHI = XHI*Ptotal= 0.5*Ptotal
Now substitute into Kp expression the partial pressures of PNH3 and PHI and you are left with only one unknown. Solve for Ptotal. After finding Ptotal, use that back in the PNH3 = XNH3*Ptotal to find PNH3.
Repost as a new problem if you run into trouble. This question is far from the top and I may miss it.
Sure, I can help you with that! To determine the partial pressure of ammonia when equilibrium is reached, you can use the ideal gas law and the concept of partial pressure.
1. Start by calculating the number of moles of ammonium iodide:
- Given mass of ammonium iodide = 150 g
- Molar mass of NH4I = 149.89 g/mol
- Moles of NH4I = mass/molar mass = 150 g / 149.89 g/mol = approximately 1.001 mol
2. Since ammonium iodide dissociates into one mole each of ammonia and hydrogen iodide, at equilibrium, you will have 1.001 mol of ammonia (NH3) and 1.001 mol of hydrogen iodide (HI) present.
3. Now, you need to find the total pressure (P_total) at equilibrium. The total pressure is the sum of the partial pressures of ammonia (P_NH3) and hydrogen iodide (P_HI).
4. The equilibrium constant Kp is given as 0.215. It is defined as:
Kp = (P_NH3 * P_HI) / P_NH4I
Rearranging the equation, we get:
P_NH3 = (Kp * P_NH4I) / P_HI
5. Since you don't have the values of P_NH3 and P_HI at equilibrium, we will assume the values to be x for P_NH3 and x for P_HI.
6. The pressure of ammonium iodide (P_NH4I) is calculated by dividing the number of moles by the volume:
P_NH4I = (1.001 mol) / (3.00 L) = approximately 0.3337 atm
7. Now, substitute the values into the equation from step 4:
x = (0.215 * 0.3337 atm) / x
Simplify the equation and solve for x.
After solving for x, you will have determined the partial pressure of ammonia (P_NH3) when equilibrium is reached.
I hope this sets you up in the right direction! Let me know if you have any further questions.
To solve this problem, we can use the ideal gas law and the equation for the equilibrium constant (Kp) to find the partial pressure of ammonia when equilibrium is reached.
1. First, let's convert the given mass of ammonium iodide (NH4I) to moles. The molar mass of NH4I is:
NH4I = (1 * 14.01 g/mol) + (4 * 1.01 g/mol) + (1 * 126.9 g/mol) = 144.1 g/mol
So, the number of moles of NH4I is:
moles of NH4I = mass of NH4I / molar mass of NH4I
moles of NH4I = 150 g / 144.1 g/mol
2. Next, calculate the initial amount of moles of NH3 and HI. At the start, there is no NH3 or HI, only NH4I. Since NH4I fully dissociates into NH3 and HI, the initial amount of NH3 and HI will be equal to the moles of NH4I.
3. Now, calculate the initial pressure (P) of the system. The initial pressure is the sum of the partial pressures of NH3 and HI, which are both zero initially.
4. Use the equation for the equilibrium constant (Kp) to find the value of the equilibrium constant:
Kp = (P(NH3) * P(HI)) / (P(NH4I))
5. Rearrange the equation to solve for P(NH3):
P(NH3) = (Kp * P(NH4I)) / P(HI)
6. Since Kp and P(HI) are given, substitute the values into the equation and solve for P(NH3).
To calculate the partial pressure of ammonia when equilibrium is reached, we need to use the equilibrium constant expression, Kp, along with the initial amount of ammonium iodide.
Given information:
- Initial amount of ammonium iodide (NH4I): 150 g
- Volume: 3.00 L
- Equilibrium constant (Kp): 0.215
First, we need to convert the mass of ammonium iodide to the number of moles:
1. Calculate the molar mass of NH4I:
Molar mass of NH4I = (1 * atomic mass of N) + (4 * atomic mass of H) + atomic mass of I
2. Convert mass to moles:
Number of moles of NH4I = Mass of NH4I / Molar mass of NH4I
Next, we will assume x moles of NH4I decomposes to form x moles each of NH3 and HI at equilibrium.
The initial pressure of NH3 (P_NH3) and HI (P_HI) is assumed to be 0.
Using the ideal gas law, we can calculate the partial pressure of NH3 (P_NH3) when equilibrium is reached:
P_NH3 = (x / 3.00 L) * R * T, where R is the ideal gas constant and T is the temperature in Kelvin.
To find x, we can use the equilibrium expression and the given value of Kp:
Kp = (P_NH3 * P_HI) / (P_NH4I)
Substitute the calculated value of P_NH3 into the above equation, rearrange it, and solve for x:
x = (Kp * (P_NH4I)) / P_HI
Now, using the number of moles of NH4I, we can determine the initial pressure of HI (P_HI):
P_HI = (number of moles of HI / 3.00 L) * R * T
Finally, substitute the values of x, P_HI, and P_NH4I back into the equation for P_NH3 to find the partial pressure of ammonia when equilibrium is reached.
I hope this helps you understand the general process. If you have any specific values or need further clarification, please let me know!