Question

(i) Nitrogen reacts with hydrogen to give ammonia. Calculate the volume of the ammonia gas formed when nitrogen reacts with 6 litres of hydrogen. All volumes measured at s.t.p.
(ii) 20ml. each of oxygen and hydrogen and 10ml. of carbon monoxide are exploded in an enclosure. What will be the volume and composition of the mixture of the gases when they are cooled to room temperature.

Answer 1

         N2  + 3 H2  => 2 N H3

One mole of N2 reacts with 3 moles of hydrogen to form 2 moles of ammonia.
one mole of a gas occupies 22.4 litres at STP.  Since there are 6 litres of Hydrogen, then there are 6/22.4 moles of H2.  Then  there are  1/3rd of that ie., 2/22.4 litres of Nitrogen that react with H2.

   Then the number of moles of ammonia formed is = 2 * 2/22.4 = 4/22.4 moles.

  The volume of ammonia =  4/22.4 * 22.4 litres = 4 litres.
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Answer 2

N2  + 3 H2  => 2 N H3

One mole of N2 reacts with 3 moles of hydrogen to form 2 moles of ammonia.

one mole of a gas occupies 22.4 litres at STP.  Since there are 6 litres of Hydrogen, then there are 6/22.4 moles of H2.  Then  there are  1/3rd of that ie., 2/22.4 litres of Nitrogen that react with H2.

  Then the number of moles of ammonia formed is = 2 * 2/22.4 = 4/22.4 moles.

 The volume of ammonia =  4/22.4 * 22.4 litres = 4 litres.