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Size of product given size of reactant?

  1. Nov 20, 2011 #1
    We have this assignment, but the teacher didn't teach us this at all.

    "For each of the following balanced chemical equations, calculate how many moles and how many grams of each product would be produced by the complete conversion of 0.56 mol of the reactant indicated in boldface."

    Here is one problem, how do I do it?

    NH3(g) + HCl(g) → NH4Cl(s)
     
  2. jcsd
  3. Nov 20, 2011 #2

    Borek

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    Staff: Mentor

  4. Nov 20, 2011 #3
    The reaction is balanced. The two products become one. How do you solve 1+1? Hint: 1+1=2
     
  5. Nov 20, 2011 #4
    She's a very terrible teacher, and the book is very general. So thanks for the help!

    Also, what does the (s) and (g) mean in the equation?


    You didn't read it all, did you?
     
    Last edited: Nov 20, 2011
  6. Nov 21, 2011 #5

    Borek

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    Staff: Mentor

    (s) for a solid, (g) for a gas. Also (l) for a liquid and (aq) for something dissolved in water.
     
  7. Nov 21, 2011 #6
    There's not much to read. Of course I read it all. What did you expect?

    You can think of this as pushing two balls of clay into one.

    You have 0.56 mol of ammonia gas. It's probably sitting in some flask, and you're pumping in hydrochloric gas from a source. You want to know how much gas to pump in so that you can convert all the molecules to ammonium chloride salt. In other words, all the ammonia molecules in the flask must react with the hydrochloric gas molecules to form the ammonium chloride salt. Therefore, you have to pump in 0.56 mol of hydrochloric gas.

    Okay... so how is this useful? The next step is to go find a periodic table. The values in the periodic table are average g/mol values of the elements. Convert all the values to grams to find the masses of each of the chemicals that you're using.

    Obviously, since mass is conserved, then the mass of the NH4Cl salt is the combined mass of the NH3 and HCl gasses. However, you still end up with the same number of mols of NH4Cl as each of the reactants. When you push two balls of clay into one, the one clay ball will have twice the mass, but regardless, it's still one clay ball.
     
    Last edited: Nov 21, 2011
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