Answer:
a. => LR is HNO₃
b. => 13.88 grams Fe(NO₃)₃
c. => 29.1%
Explanation:
a. Limiting Reactant:
Note => Determining LR is quite simple if you'll convert all data to moles and divide each mole value by the respective coefficient. The smaller value is the limiting reactant.
Given: Fe + 6HNO₃ ⇒ Fe(NO₃)₃ + 3NO₂ + 3H₂O
20.3g 21.4g
= 20.3g/56g/mole =21.4g/63g/mole
= 0.363 mole = 0.340 mole
Divide by coefficient 1 Divide by coefficient 6
= 0.363/1 = 0.363 = 0.340/6 = 0.057
Since 0.057 is the smaller value then HNO₃ is the limiting reactant. However, one must use the calculated mole values when applying to equation stoichometry.
b. Grams of Fe(NO₃)₃ Produced:
Problems like this can be greatly simplified if data is 1st converted to moles and solved with respect to equation reaction ratios. Then convert mole value to needed dimension.
Fe + 6HNO₃ ⇒ Fe(NO₃)₃ + 3NO₂ + 3H₂O
Rxn Ratio between LR and Fe(NO₃)₃ => 1:6
0.340 mole HNO₃ => 1/6(0.340mole Fe(NO₃)₃ Produced = 0.057mole Fe(NO₃)₃ x 242 g/mole = 13.8 grams of Fe(NO₃)₃ produced
c. Percent Yield:
Given: Fe + 6HNO₃ ⇒ Fe(NO₃)₃ + 3NO₂ + 3H₂O
Measured Lab Yield = 4.02 grams (given in problem)
Theoretical Yield = 13.8 grams (calculated in part b)
%Yield = (Lab Yield/Theoretical Yield)100%
= (4.02/13.8)100% = 29.1% (w:w)*
*w:w means calculation was based on weight values and not volume values.
