Analía Bellizzi – Chemistry Classes

Ronald Reagan Senior High School

Percent Yield Exercises


Review from Stoichiometry  Simple

1. Lead(II) sulfide, PbS, reacts with oxygen gas to produce lead(II) oxide and sulfur dioxide. If 0.500 moles of O2 were consumed using this chemical reaction, how many grams of lead(II) oxide would be produced? (Ar: O=16; Pb=207; S=32) Ans: 74.3  

2 PbS + 3 O2  2 PbO + 2 SO2

2. Potassium chlorate, KClO3, decomposes when heated to produce potassium chloride and oxygen gas. If 2.50 grams of KClO3 were heated in a test tube, how many grams of oxygen gas should be given off? (Ar: O=16; Cl=35.5; K=39) Ans: 0.980 g

2 KClO 2 KCl + 3 O2

Percent Yield


3. The reaction between 15.8 g of NH3 and excess oxygen gas produces 21.8 g of NO gas and some water.  Determine the percent yield. (Ar: O=16; N=14; H=1) Ans: 78.19

4 NH+ 5 O24 NO + 6 H2O

4. For the balanced equation shown below, if the reaction of 77.0 grams of CaCN2 produces 27.1 grams of NH3, what is the percent yield? (Ar: O=16; N=14; H=1; Ca=40; C=12) Ans: 82.8

CaCN+ 3 H2 CaCO+ 2 NH3

5. For the balanced equation shown below, if the reaction of 91.3 grams of C3H6 produces at 81.3% yield, how many grams of CO2 would be produced? (Ar: O=16; H=1; C=12) Ans: 233

2 C3H+ 9 O6 CO+ 6 H2O

6.  For the balanced equation shown below, if the reaction of 20.7 grams of CaCO3 produces 6.81 grams of CaO, what is the percent yield?(Ar: O=16; Ca=40; C=12) Ans: 58.75

 CaCOCaO + CO2

7. Given the following equation and  you start with 389.4 g of Al2(SO3)3 and you isolate 212.4 g of Na2SO3, what is your percent yield for this reaction?
(Ar: O=16; Al=27; Na=23; S=32; H=1) Ans: 42.42% 

Al2(SO3)3    +  6 NaOH    3Na2SO3    +   2 Al(OH)3