Question

(Yield Problem)

3Mg+2FeCl3=2Fe+3MgCl2
When 20.5 g of Mg reacts with an excess of FeCl3, 25.9 g of Fe is produced. What is the percent
yield of the reaction?

Answer 1

Percent Yield Fe = 82.5%

Step-by-step explanation:

The actual yield is the value produced after an experiment is conducted. The theoretical yield is the value calculated using the balanced chemical equation and atomic/molar masses.

To find the percent yield of iron (Fe), you need to (1) convert grams Al to moles Al (via atomic mass), then (2) convert moles Al to moles Fe (via mole-to-mole ratio from equation coefficients), then (3) convert moles Fe to grams Fe (via atomic mass), and then (4) calculate the percent yield. It is important to arrange the ratios in a way that allows for the cancellation of units. The final answer should have 3 sig figs to reflect the sig figs of the given values.

Atomic Mass (Mg): 24.305 g/mol

Atomic Mass (Fe): 55.845 g/mol

3 Mg + 2 FeCl₃ -----> 2 Fe + 3 MgCl₂

20.5 g Mg 1 mole 2 moles Fe 55.845 g
----------------- x ----------------- x ---------------------- x ----------------- =
24.305 g 3 moles Mg 1 mole

= 31.4 g Fe

Actual Yield
Percent Yield = ---------------------------------- x 100%
Theoretical Yield

25.9 g Fe
Percent Yield = -------------------- x 100%
31.4 g Fe

Percent Yield = 82.5%