Percent yield calculator

What is a percent yield calculator?

A percent yield calculator is a free onlinetool used in chemistry to determine the yield of a product reaction as a percentage of the theoretical yield. It compares the actual yield obtained from a chemical reaction to the maximum possible yield, expressing this relationship as a percentage. This calculator is valuable in analyzing reactions to understand their completeness and to identify factors that might have affected the outcome.

Importance of understanding yield fraction

Understanding the yield fraction—that is, the ratio of the actual yield to the theoretical possible yield—is a crucial metric in chemical experiments. It helps assess the efficiency of chemical reactions and pinpoint potential losses or errors. In both laboratory and industrial settings, percent yield aids in determining the economic efficiency of processes by ensuring maximum utilization of reactants at minimal cost.

Factors influencing yield fraction

Several factors can influence the yield fraction, including the purity of reactants, reaction conditions (temperature, pressure), the presence of side reactions, and mechanical losses. Recognizing and understanding these factors assists chemists in optimizing procedures to increase the yield of useful products.

Formula

Percent yield is calculated using the following formula:

$\text{Percent Yield} = \left( \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \right) \times 100\%$

Where:

• Actual Yield is the amount of product actually obtained from the reaction.
• Theoretical Yield is the maximum amount of product that could be formed, assuming complete and perfect reaction.

Examples

Example 1: Neutralization reaction

Consider the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) to form sodium chloride (NaCl) and water (H2O):

$\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}$

If the calculated theoretical yield of NaCl is 58.5 g, but the actual yield obtained is 50 g, the percent yield will be:

$\left( \frac{50}{58.5} \right) \times 100\% \approx 85.47\%$

This means the fraction of NaCl yield to the theoretically possible amount is 85.47%.

Example 2: Combustion reaction

Consider the combustion of methane (CH4) with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O):

$\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}$

If the theoretical yield of water is 36 g, and the actual yield is 30 g, the percent yield is:

$\left( \frac{30}{36} \right) \times 100\% = 83.33\%$

Hence, the water yield was 83.33% of the theoretical maximum.

Notes

• Precision in measuring both actual yield and theoretical yield is essential for accurate calculations.
• When calculating the theoretical yield, consider the stoichiometry of the reaction and possible side reactions.

FAQ

What is actual yield expressed as a percentage?

Actual yield is the quantity of substance actually produced from a reaction, expressed as a percentage of the theoretically expected amount, calculated based on stoichiometry.

Why is the actual yield often less than the theoretical yield?

There are many reasons why actual yield may be less than theoretical yield, such as losses during filtration or purification, incomplete reactions, side reactions, or measurement errors.

What is the typical percentage yield in laboratory conditions?

Percent yield in laboratory conditions can vary considerably depending on the reaction and conditions under which it is conducted. It typically ranges from 50% to 90%, but under ideal conditions can reach up to 100%.

What should be done if the percent yield exceeds 100%?

A percent yield exceeding 100% typically indicates an error in calculations or measurements. It is important to review the data, including the mass of starting materials and products, to identify possible inaccuracies.

What is the actual yield of benzene given a theoretical yield of 25 g, assuming a percent yield of 73%?

Let’s break down the calculation:

1. Given: Theoretical Yield = 25 g.
2. Given: Percent Yield = 73%.
3. Formula to find the actual yield:

$\text{Actual Yield} = \left( \frac{\text{Percent Yield}}{100} \right) \times \text{Theoretical Yield}$

4. Substitute the known values:

$\text{Actual Yield} = \left( \frac{73}{100} \right) \times 25 = 18.25\ g$

Thus, the actual yield of benzene is 18.25 g. This indicates that the efficiency of the reaction achieved 73% of the theoretical maximum.