1. Limited React./Chem. yield [Law of definite proportions] → 1.0 g H 2 + 8.0 g O 2 → 9.0 g H 2 O However, A chemist combines and reacts 3.0 g of H 2 with 4.0 g of O 2. 3.0 g H 2 + 4.0 g O 2 → ? g H 2 O NOTE: O 2 is the “limiting reactant.” 1.What mass (theoretical mass) of water results? ANS: 4.5g 2.If you were doing this experiment, what mass of water would you probably get? It would probably be <4.5g ( Maybe 3.1 g?) 3. % yield = Actual yield/Theoretical yield X 100 = 3.1 g/4.5 g X 100 = 60.9%

2. Limited React./Chem. yield A chemist reacts 20g of potassium hydroxide with 30 g of phosphoric acid to produce potassium phosphate and water. 1. Write and balance the chemical equation. 2. Determine the limiting reactant? (ANS: 51.5 g KOH reacts with 30 g of H 3 PO 4 OR 11.6 g of H 3 PO 4 reacts with 20 g of KOH.) CONCLUSION: KOH is depleted, and there is excess H 3 PO 4. KOH is the limiting reactant. 3. KOH is the limiting reactant. Calculate the theoretical yield of potassium phosphate. ANS: 25.2 g 4. The published yield is 65%. Calculate the actual yield. ANS: 16.4g

3. Limited React./Chem. yield A chemist reacts 78 mg of aluminum with 15.5 mL 0.358 M copper (II) nitrate solution producing aluminum nitrate and copper. 1. Write and balance the chemical equation. 2. Determine the limiting reactant? ANS: Al (100 mg of Al reacts with 15.5 mL 0.358 M copper nitrate OR 12.1 mL of 0.358 M copper (II) nitrate solution reacts with 78 mg aluminum.) 3. Calculate the theoretical yield (mass) of copper formed. ANS: 0.276g 4. The chemist actually produces 0.200g of copper. Calculate the % yield. ANS: 72.5% 5. Write the complete ionic and net ionic equation.

4. Limited React./Chem. yield A chemist reacts 58 mL of 0.256 M sodium hydroxide with 23 mL of 0.185 M phosphoric acid. 1.Determine the limiting reactant. ANS: [Phosphoric acid] 26.7 mL of 0.185 M phosphoric acid reacts with 58 mL of 0.256 M sodium hydroxide OR 5.0 mL of 0.256 M sodium hydroxide reacts with 23 mL of 0.185 M phosphoric acid. 2.Is the mixture acidic or basic? 3.Calculate the theoretical yield of sodium phosphate.

5. Limited React./Chem. yield 375 g of ethyne (C 2 H 2 ) reacts with 1.0 pt. (454g) of water to form ethanal (CH 3 CHO) with a 42% yield. NOTE: Ethyne is also acetylene. Ethanal is also acetaldehyde. 1. Determine the limiting reactant. ANS: C 2 H 2 2. Calculate the theoretical yield of ethanol. ANS: 635g 3. Calculate the actual yield of ethanal. ANS: 267g

6. Limited React./Chem. yield Acetic acid (CH 3 COOH) reacts with phosphorus trichloride to form acetyl chloride (CH 3 COCl) and phosphorus acid (H 3 PO 3 )The acetyl chloride yield for this reaction is 70%. 1. Write a balanced chemical equation. 2. Calculate the theoretical mass of acetyl chloride necessary to actually produce 1.0 lb (456 g) of acetyl chloride. ANS: 651g 3. Calculate the mass of acetic acid necessary to actually produce 1.0 lb (456 g) of acetyl chloride. ANS: 498g