Calculate how many moles of NH3 form when 3.55 moles of N2H4 completely react according to the equation: 3N2H4 (l) ---> 4NH3 (g) + N2 (g) ?

1 Answer
Nathan L.
Jun 15, 2017

4.73 "mol NH"_3

Explanation:

What we're doing here is calculating basic mole-mole relationships, something that you'll be doing quite a bit!

The steps to solving mole-mole problems like this are

  • write the balanced chemical equation for the reaction (this is given)

  • divide the number of moles of the given known substance (3.55) by that substance's coefficient in the chemical equation (3)

  • multiply that number by the coefficient of the substance you're trying to find (4)

Using simple dimensional analysis, it looks like this:

3.55cancel("mol N"_2"H"_4)(larr "given amount")((4"mol NH"_3("coefficient"))/(3cancel("mol N"_2"H"_4)("coefficient")))

= color(red)(4.73 color(red)("mol NH"_3

rounded to 3 significant figures, the amount given in the problem.

Thus, if the reaction goes to completion, 3.55 moles of "N"_2"H"_4 will yield color(red)(4.73 moles of "NH"_3.

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