Question

how many molecules (not moles) of nh3 are produced from 1.36×x10−4 g of h2

Answer 1

The reaction of nitrogen(N₂) and hydrogen(H₂) to produce ammonia is as follows

N₂ + 3H₂    2NH₃

according to the equation

3 moles of hydrogen react with 1 mole of nitrogen to give 2 moles of ammonia.

1 mole of hydrogen weighs 2 g, therefore 3 moles of hydrogen weighs 6 g and 1 mole of ammonia weighs 17 g and thus 2 moles of ammonia weighs 34 g.

this implies that 6 g of hydrogen gives 34 g of ammonia

hence 1 gram of hydrogen gives 34/6 g of ammonia

therefore, 1.36 x 10^-4 g of hydrogen gives 34 x 1.36 x 10^-4 / 6

= 7.70 x 10^-4 g of ammonia.

now, number of moles of ammonia are 7.70 x 10^-4 / 17

= 4.5 x 10^-5 moles

1 mole of ammonia contains 6.023 x 10²³ molecules.

therefore 4.5 x 10^-5 moles of ammonia contains 4.5 x 10^-5 x 6.023 x 10²³

     = 2.71 x 10¹⁹ molecules