Question

How many molecules (not moles) of nh3 are produced from 6.96×10−4 g of h2? express your answer numerically as the number of molecules?

Answer 1

number of moles = mass / molar mass
number of moles of H2 = (6.96×10−4) / (2)(1) = 3.48*10^-4 moles

The equation that describes the formulation of NH3 is:
N2 + 3H2 .......> 2NH3
From the balanced chemical equation, we can see that:
3 moles of H2 produces 2 moles of NH3
Based on this, to know the number of moles of NH3 produced from 3.48*10^-4 moles of hydrogen, we will do cross multiplication as follows:
number of moles = (3.48*10^-4*2) / (3) = 2.32*10^-4 moles

Now, one mole of any element contains Avogadro's number of molecules. Therefore, number of molecules in 2.32*10^-4 moles can be calculated as follows:
number of molecules = 2.32 * 10^-4 * 6.022 * 10^23 = 1.397 * 10^20 molecules