The video tutorial by Mr. Donny explains the concept of percent yield in chemistry, which measures the efficiency of a chemical reaction. It covers the formula for percent yield, which is the actual yield divided by the theoretical yield, multiplied by 100. The tutorial includes two example problems: one simple calculation and another involving a limiting reactant. The video emphasizes the importance of accurate calculations and warns against yields over 100%, indicating errors. The tutorial concludes with a summary of the steps to determine percent yield.

What is the main objective of learning about percent yield?

• To determine the efficiency of a chemical reaction

• To find the color change in reactions

• To calculate the cost of reactants

• To measure the temperature of reactions

Why is it rare to achieve a 100% theoretical yield in chemical reactions?

• Because of incorrect reactant ratios

• Because of measurement errors

• Due to loss of product during the process

• Due to impurities in reactants

How is percent yield calculated?

• Theoretical yield minus actual yield times 100

• Theoretical yield divided by actual yield times 100

• Actual yield divided by theoretical yield times 100

• Actual yield plus theoretical yield times 100

In the simple example given, what was the percent yield if the actual yield was 1435 grams and the theoretical yield was 1800 grams?

• 85.0%

• 75.0%

• 80.0%

• 79.7%

What is the first step in determining the percent yield in a detailed example?

• Measuring the reactants

• Identifying the limiting reactant

• Calculating the theoretical yield

• Finding the actual yield

How do you convert grams of a reactant to moles?

• Add the formula mass

• Subtract the formula mass

• Multiply by the formula mass

• Divide by the formula mass

What is the mole ratio of N2 to H2 in the given example?

• 1:2

• 3:1

• 1:3

• 2:3

If the limiting reactant is N2, how do you determine the theoretical yield of NH3?

• Use the mole ratio of N2 to NH3

• Divide the moles of N2 by the formula mass of NH3

• Use the mole ratio of H2 to NH3

• Multiply the moles of N2 by the formula mass of NH3

What is the theoretical yield of NH3 in grams if the moles of NH3 are 1.928 and the formula mass is 17.04?

• 32.9 grams

• 30.0 grams

• 35.0 grams

• 28.0 grams

What should you do if you calculate a percent yield greater than 100%?

• Assume the reaction was perfect

• Recheck your math for errors

• Ignore the result

• Increase the amount of reactants