posted by Nina

A chemist wants to prepare phosgene, COCl2, by the following reaction: CO(g) + Cl2(g) COCl2(g) He places 2.60 g of chlorine, Cl2, and an equal molar amount of carbon monoxide, CO, into a 10.00 L reaction vessel at 395 °C. After the reaction comes to equilibrium, he adds another 2.60 g of chlorine to the vessel in order to push the reaction to the right to get more product. What is the partial pressure of phosgene when the reaction again comes to equilibrium? Kc = 1.23E+3.

  1. DrBob222

    These numbers are estimates so you need to go through and recalculate all of them.
    (Cl2) = mols/L = 2.60/71/10 = about 0.004M
    (CO) = 0.004 (actually closer to 0.00366).
    ..........CO + Cl2 ==> COCl1

    Kc = (COCl2)/(CO)(Cl2)
    1.23E3 = (x)/(0.004-x)^2
    solve for x and I obtained about 0.002
    At the 1st equilibrium (CO) = 0.004-0.002 = bout 0.002 and (Cl2) = about 0.002 with (COCl2) = about 0.002

    So now set up a second ICE chart like this
    ..........CO + Cl2 ==> COCl2

    Substitute into Kc and solve for x = M COCl2.
    Then convert to mols COCl2 and use PV = nRT to solve for pressure.
    Post your work if you get stuck. Remember those numbers I've used are estimates and I've rounded extensively.

  2. Nina

    Thank you but i'm not understanding how you got .002 for x

  3. DrBob222

    You solve the equation.
    mols Cl2 = 2.60/71 = 0.0366
    M Cl2 = mols/L = 0.0366/10 = 0.00366
    M CO = 0.00366

    Kc = (COCl2)/(CO)(Cl2)
    1.23E3 = [(x)/(0.00366-x)^2]
    1.23E3*(0.00366-x)^2 = x
    1.23E3*(0.00366-x)(0.00366-x) = x
    and go from there.
    x = 0.0023 I believe although I've thrown my work away.
    Then (CO) = (Cl2) = 0.00366-x = 0.00366-0.0023 = 0.00136M
    Check these numbers correctly. I worked it through the first equilibrium and those numbers are what I remember. Perhaps I just don't remember correctly. Then you go through the second equilibrium as I've shown and finally use PV = nRT

  4. Andrew P.

    How do you get moles of COCl2 from the [COCl2].

    Instead of using PV=nRT to find the partial pressure, shouldn't I use Kp=Kc(RT)^delta(n)

  5. DrBob222

    After you go through the equilibrium the second time you end up with M COCl2.
    You know M = mols/L. You know M from your calculation and you know L (10L) so
    mols = M x L = ? = n and use PV = nRT to solve for pressure. No, you don't go through the Kp thing because there is no pressure in that equation. If you want pressure, the only way to get it is to use PV = nRT. You could have converted Kc to Kp if you wish but since you are given concentrations it is easier to use Kc from the beginning, especially since that is what is given.

Respond to this Question

First Name

Your Answer

Similar Questions

  1. chemistry

    Phosgene (COCl2) is an extremely poisonous gas that was used extensively in World War I as a chemical warfare agent. At 300oC, phosgene decomposes to carbon monoxide and chlorine with a Kp = 6.8 x 10-2. Calculate the pressure in the …
  2. Chemistry

    Pure phosgene gas (COCl2), .03mole, was placed in a 1.5 L container. It was heated to 800k, and at equilibrium the pressure of CO was found to be .497 atm. Calculate the equilibrium constant Kp for the reaction CO(g) + Cl2(g) = COCL2(g)
  3. Chemistry

    Pure phosgene gas (COCl2), .03mole, was placed in a 1.5 L container. It was heated to 800k, and at equilibrium the pressure of CO was found to be .497 atm. Calculate the equilibrium constant Kp for the reaction CO(g) + Cl2(g) = COCL2(g)
  4. Chemistry

    the initial pressure of phosgene gas (COCl2), was 1.31 atm. it was heated, and at equilibrium the pressure of CO was found to be .547 atm. what are the equilibrium pressures of Cl2 and COCl2?
  5. Chemistry

    The equilibrium constant Kc for the following reaction is equal to 0.20 at 250°C. Calculate the equilibrium constant Kp for the reverse reaction at the same temperature. COCl2 (g) = CO (g) + Cl2 (g) I'm sorry.. English is a second …
  6. Chem

    Consider 1.40 mol of carbon monoxide and 3.20 mol of chlorine sealed in a 8.00 L container at 476 oC. The equilibrium constant, Kc, is 2.50 (in M-1) for CO(g) + Cl2(g) ↔ COCl2(g) Calculate the equilibrium molar concentration …
  7. HARD CHEM QUESTION- any help appreciated

    Phosgene (COCl2) is a poisonous gas that dissociates at high temperature into two other poisonous gases, carbon monoxide and chlorine with equilibrium constant Kp = 0.0041 at 600 K. Find the equilibrium composition of the system after …
  8. Chemistry

    Carbon monoxide and chlorine gas react to form phosgene: CO(g)+Cl2(g)⇌COCl2(g) Kp = 3.10 at 700 K If a reaction mixture initially contains 319torr of CO and 220torr of Cl2, what is the mole fraction of COCl2 when equilibrium …
  9. scince

    Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic gases, phosgene and chlorine. CCl4(g) + 1/2O2(g) COCl2(g) + Cl2(g), Kc = 4.4 × 109 at 1,000 K Calculate Kc for the reaction 2CCl4(g) + O2(g) 2COCl2(g) …
  10. chemistry

    Phosgene is a potent chemical warfare agent that is now outlawed by international agreement. It decomposes by the reaction CoCl2(g)=>Co(g) + Cl2(g), Kc=8.3×10^-4.calculate [CoCl2] when 0.100mol CoCl2 decomposes and reach equilibrium …

More Similar Questions