Understanding Percentage Yield

This lesson explains percentage yield, a measure of reaction efficiency, and how to calculate it. Theoretical yield is predicted based on reactants, but practical yield is often lower due to inefficiencies. The video uses examples, such as ethene and water producing ethanol, and aspirin production, to demonstrate calculations. By dividing actual yield by theoretical yield and multiplying by 100, percentage yield is determined. High percentage yield indicates efficient reactions with minimal waste. The lesson concludes with the importance of understanding and improving yield in industrial processes.

What does percentage yield indicate in a chemical reaction?

• The speed of the reaction

• The temperature of the reaction

• The efficiency of the reaction

• The color of the products

In the reaction of ethene and water, what is the theoretical mass of ethanol formed?

• 18 grams

• 42 grams

• 28 grams

• 46 grams

Why is the practical mass of a product often less than the theoretical mass?

• Because of the color of the reactants

• Due to the purity of reactants

• Because of incorrect measurements

• Due to the inefficiency of the reaction process

How do you calculate percentage yield?

• Theoretical yield divided by actual yield, multiplied by 100

• Actual yield plus theoretical yield, multiplied by 100

• Theoretical yield minus actual yield, multiplied by 100

• Actual yield divided by theoretical yield, multiplied by 100

In the example given, what was the percentage yield of ethanol?

• 85%

• 91.3%

• 100%

• 95%

What can be done to improve reaction efficiency in industry?

• Increase the temperature

• Modify methods to improve yield

• Use more reactants

• Change the color of the reactants

What unit can be used to calculate yield at higher levels?

• Kilograms

• Moles

• Liters

• Grams

In the aspirin example, what was the actual yield in moles?

• 0.80 moles

• 0.70 moles

• 0.755 moles

• 0.74 moles

What was the percentage yield in the aspirin example?

• 100%

• 98%

• 90%

• 95%

What does a high percentage yield indicate about a reaction?

• It is efficient with little loss

• It is inefficient

• It is very slow

• There is a lot of waste