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Homework Help: Chemistry: would someone verify my work, please?

  1. Apr 1, 2008 #1
    1. The problem statement, all variables and given/known data

    Assume that coal can be represented by the formula C135H96O9NS. A. What is the percent of nitrogen by mass in this coal? B. If three tons of coal were burned completely, what mass of nitrogen in NO would be produced? (Assume that all of the nitrogen in the coal is converted to NO in the burning process.) Be sure to show all your calculation work in each case.

    3. The attempt at a solution

    A.135x12.01=1621.35 (carbon) + 96x1.008=96.76 (hydrogen) + 9x16.00=144 (oxygen) + 1x14.01=14.01 (nitrogen) + 1x32.07=32.07 (sulfur) = 1908.19. 14.01x100/1908.19= 0.734%.

    B.First, to find the moles of coal in 6000lbs of coal, I converted the pounds to grams and divided it by the mole weight (6000 x 453.6 / 1908.19 = 1426.27). Since one mole of coal provides one mole of NO, there are 1426 moles of coal and 1426 moles of Nitrogen. NO has a molar mass of 30g/mol, so 30g/mol x 1426 moles = 42.8kg of NO. Therefore, the mass of nitrogen in NO that would be produced when three tons of coal is burned completely is 42kg. (Am I including both nitrogen and oxygen in this figure? I'm only suppose to be looking for nitrogen??)

    I want to make sure I have done this right. If not, please point me in the right direction:)
    Last edited: Apr 1, 2008
  2. jcsd
  3. Apr 1, 2008 #2
    So you've got 42.8 kg of NO. They want to know how much of this is nitrogen.
  4. Apr 1, 2008 #3
    Is 42.8kg the correct number of NO? Is there a formula to use to find how much of this is N?
  5. Apr 1, 2008 #4
    I've checked your work and it seems that that is the correct answer.

    Think about 1 mol of NO. What percent of this (in terms of mass) is nitrogen?
  6. Apr 1, 2008 #5


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    The question asks you for the mass of NO, not N. Relax, you have it. You might want to express it in either tons or pounds for completeness.
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