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2009 ADA Test (#41 and #65)

Discussion in 'DAT Discussions' started by Delegate, Aug 1, 2011.

  1. Delegate

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    Hi all,

    This is for those who have been practicing with 2009 practice test. I'm having trouble with #41 and #65. Please help!

    41) Exactly 492g of kerosene are required to fill a certain container. If the density of the kerosene was 0.820g/ml-1, and at the same temperature the density of mercury was 13.5g/ml-1, then what mass of mercury in grams, would be necessary to fill the container?

    65)Consider the equilibrium rxn: 2NO(g) + O2 (g)-->2 NO2 (g), K = 2.0.
    Which of the following is the correct value of K for the reaction :
    NO2(g)--> NO(g) + 1/2O2(g)?

    Thank you!
     
  2. PooyaH

    2+ Year Member

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    1. You need to get the volume of the container first, so since the density is .82g/ml and you have 492g of kerosene, then .82g/ml = 492g/ml, ml = 492/.82 = 600ml

    Since you're filling up the same container, use the same volume to get the grams of Mercury: 13.5g/ml = g/600ml, g of Mercury = (13.5g/ml)(600ml) = 8100g of Mercury

    2. Since the moles of reaction has been cut in half, the new K = square root of K, and since it is showing the reverse reaction, the K has to be 1/K. So if you put those two together, you'd have 1/sq rt of 2.
     
  3. OP
    OP
    Delegate

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    Thank you, thank you!!
     

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