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Thread: AP Chemistry Challenge

  1. #1 AP Chemistry Challenge 
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    AP-level Chemistry challenge question:

    Permanganic acid (350 ml of a 2.0M aqueous solution) is reacted with 2.0 L of 2.0 N hydrochloric acid, producing aqueous manganese (II) chloride and chlorine gas. The hydrochloric acid was made with pure radioactive chlorine-33, which has a half-life of 37.24 minutes and undergoes β− decay. The reaction is conducted in a sealed 25 L vessel at an initial pressure of 99.5 kPa. The vessel is kept at a constant temperature of 25°C throughout the reaction. What is the pressure inside the vessel after 75 minutes? What assumptions need to be made when solving this problem?


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  3. #2  
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    ...and how does that help?


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  4. #3  
    Moderator Moderator AlexP's Avatar
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    Don't mind him, he's just a spammer. I deleted the post so no one links to his site.

    What thoughts have you had about this question? Have you made any progress on it?
    "There is a kind of lazy pleasure in useless and out-of-the-way erudition." -Jorge Luis Borges
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  5. #4  
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    well i did the redox half reactions and combined them for an overall reaction of:

    MnO4- + 3Cl2 + 8H+ ---> Mn2+ + 4H20 + 6HCl-

    so there are 3 moles of gas in the system, and the beta decay, i assumed to be negligible, since it doesnt affect mass. so the initial number of moles, based on

    PV=nRT, is 1.004 moles, and since the equation tells us it is 3, I did a ratio to find a pressure of 0.329 atm. But i dont feel that this is correct, and that i forgot stuff
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