Stoichiometry Grams to Grams

Question

2 NaN₃—> 2 Na + 3 N₂

1) Given 0.38 grams of N₂ how many grams of NaN₃ are needed ?

2) Given 5.86 grams of NaN_3, how many grams of Na are produced ?

Answer 1

In each case the coefficients in the balanced chemical equation are used as the mole ratio in order to relate moles of one substance to moles of another. Before doing this we convert the given mass in each question to moles and then can relate moles of the given substance to moles in what we're interested in converting to. Once we know moles of the desired substance we can relate to mass through the molar mass.

1. 0.38 g N₂ x (1 mol N₂/28.02 g N₂) x (2 mol NaN₃/3 mol N₂) x (65.02 g NaN₃/1 mol NaN₃) = 0.59 grams NaN₃

2. 5.86 g NaN₃ x (1 mol NaN₃/65.02 g NaN₃) (2 mol Na/2 mol NaN₃) x (22.99 g Na/1 mol Na) = 2.07 grams Na