Help pl When heated, lithium reacts with nitrogen to form lithium nitride:

Li(s) + N2(g) > Li3N(s)

What is the theoretical yield of Li3N in grams when 12.3 g of Li are heated with 33.6 g of N2?

If the actual yield of Li3N is 5.89 g, what is the percent yield of the reaction?

Percent yield =28.7%

Theoretical yield  = 20.55 g

Explanation:

Given data:

Mass of Li₃N = ?

Mass of Li = 12.3 g

Mass of N₂ = 33.6 g

Actual yield = 5.89 g

Percent yield = ?

Solution:

Chemical equation:

6Li + N₂     →       2Li₃N

Number of moles of Li:

Number of moles = mass/molar mass

Number of moles = 12.3 g / 6.9 g/mol

Number of moles = 1.78 mol

Number of moles of N₂:

Number of moles = mass/molar mass

Number of moles = 33.6 g / 28 g/mol

Number of moles = 1.2 mol

Now we will compare the moles of both reactant with product.

                 N₂         :         Li₃N

                  1           :           2

                1.2          :       2/1×1.2 = 2.4 mol

                Li           :         Li₃N

                 6           :           2

                1.78        :       2/6×1.78 =  0.59 mol

Less number of moles of Li₃N are produced by Li thus it will be act as limiting reactant.

Mass of Li₃N: Theoretical yield

Mass = number of moles × molar mass

Mass = 0.59 mol × 34.83 g/mol

Mass = 20.55 g

Percent yield:

Percent yield = ( Actual yield / theoretical yield ) × 100

Percent yield =  ( 5.89 g/ 20.55 g) × 100

Percent yield =28.7%