Question

At the start of Lab, a student is given 462 μL of cis-stilbene. Following the bromination reaction, the student obtained 0.767 g of product (MW = 340.05 g/mol). Calculate the theoretical and percent yields of the reaction assuming cis-stilbene is the limiting reagent. Show all steps of your calculations and include all units.

Answer 1

volume of cis-stilbene = 462 μL = 462 x 10^-3 mL

density of cis-stilbene = 0.971 g/ml

mass of cis-stilbene = 0.4486 g

molar mass of cis-stilbene = 180.25 g/mol

moles of cis-stilbene = 0.4486 / 180.25 = 2.489 x 10^-3

these are 1 : 1 ratio

moles of cis-stilbene = moles of product .

moles of product = 2.489 x 10^-3

theoretical yield = 2.489 x 10^-3 x 340.05

theoretical yield = 0.846 g

% yield = (actual / theoretical ) x 100

= (0.767 / 0.846 ) x 100

percent yield = 90.7 %