How To Calculate Theoretical Yield and Percent Yield

The Organic Chemistry Tutor
25 Apr 201506:24
EducationalLearning
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TLDRThe video script provides a step-by-step guide on calculating the theoretical and percent yield of a compound, using propane combustion as an example. It emphasizes the importance of writing a balanced chemical equation and identifying the limiting reactant, which is crucial for determining yields. The script explains how to convert grams of propane to moles, apply the molar ratio to find moles of CO2, and then convert back to grams to calculate the theoretical yield. With an actual yield of 70 grams of CO2 obtained from an experiment, the theoretical yield is calculated to be 90 grams, leading to a percent yield of approximately 77.8%. This informative summary captures the essence of the video, highlighting the process of yield calculation in a clear and engaging manner.

Takeaways
  • 🧪 **Balanced Equation**: To calculate yield, start with a balanced chemical equation for the reaction, ensuring all atoms are accounted for.
  • 🔥 **Combustion Reaction**: In a combustion reaction like propane with oxygen, the products are always carbon dioxide (CO2) and water (H2O).
  • 📜 **Limiting Reactant**: Identify the limiting reactant when calculating theoretical and percent yield, as it dictates the maximum amount of product that can be formed.
  • 📊 **Percent Yield Formula**: The percent yield is calculated by dividing the actual yield by the theoretical yield and multiplying by 100%.
  • 🔍 **Theoretical vs. Actual Yield**: The theoretical yield is the maximum amount of product possible from a reaction, while the actual yield is the amount actually produced.
  • ⚖️ **Molar Conversion**: Convert grams of the reactant to moles using the molar mass to find the theoretical yield.
  • 🔗 **Molar Ratio**: Use the molar ratio from the balanced equation to convert moles of one substance to moles of another.
  • 🧮 **Cancel Units**: When converting between grams and moles, ensure that units cancel out appropriately to find the correct yield in grams.
  • 📉 **Efficiency Consideration**: No reaction is 100% efficient; actual yields are typically less than theoretical yields due to various factors.
  • 📚 **Given Information**: The actual yield of CO2 in the example is provided as 70 grams, which is used to calculate the percent yield.
  • 🧠 **Understanding Calculation**: The theoretical yield is calculated to be 90 grams of CO2 from 30 grams of propane, leading to a percent yield of approximately 77.8%.
Q & A

  • What is the first step in calculating the theoretical and percent yield of a compound?

    -The first step is to write a balanced chemical equation for the reaction.

  • What is the role of propane (C3H8) in the given chemical reaction?

    -Propane (C3H8) is the compound that reacts with oxygen gas during the combustion reaction to produce carbon dioxide and water.

  • Why are carbon atoms balanced first in a combustion reaction?

    -Carbon atoms are balanced first because they are typically the most straightforward to balance and can help determine the necessary coefficients for other elements in the reaction.

  • What are the products of a combustion reaction involving propane?

    -The products of a combustion reaction involving propane are carbon dioxide (CO2) and water (H2O).

  • What is the concept of limiting reactant and excess reactant in a chemical reaction?

    -The limiting reactant is the reactant that will be completely consumed and determines the maximum amount of product that can be formed. The excess reactant is present in amounts exceeding what is required to react with the limiting reactant.

  • How is the percent yield calculated?

    -The percent yield is calculated by dividing the actual yield by the theoretical yield and then multiplying by 100 percent.

  • What is the theoretical yield in a chemical reaction?

    -The theoretical yield is the maximum amount of product that can be produced from a given amount of reactant, assuming 100% efficiency in the reaction.

  • What is the actual yield in the provided script?

    -The actual yield in the provided script is 70 grams of carbon dioxide (CO2).

  • How many grams of propane (C3H8) are used in the script to calculate the theoretical yield?

    -30 grams of propane (C3H8) are used in the script to calculate the theoretical yield.

  • What is the molar mass of carbon dioxide (CO2) used in the calculation?

    -The molar mass of carbon dioxide (CO2) is 44 grams per mole.

  • What is the calculated theoretical yield of CO2 from 30 grams of C3H8?

    -The calculated theoretical yield of CO2 from 30 grams of C3H8 is 90 grams.

  • What is the percent yield of the reaction based on the actual and theoretical yields provided?

    -The percent yield of the reaction is 77.8 percent, calculated by dividing the actual yield (70 grams) by the theoretical yield (90 grams) and multiplying by 100.

Outlines
00:00
🔍 Understanding Theoretical and Percent Yield Calculations

This paragraph introduces the topic of calculating the theoretical and percent yield of a compound, starting with the necessity of writing a balanced chemical equation. The example given involves the combustion of propane (C3H8) with oxygen gas to produce carbon dioxide and water. The process of balancing the chemical equation is explained step by step, focusing on the conservation of carbon and hydrogen atoms and the subsequent balancing of oxygen atoms. The concept of limiting and excess reactants is introduced, with an emphasis on using the limiting reactant to calculate theoretical and percent yield. The theoretical yield is defined as the maximum amount of product that can be obtained if the reaction is 100% efficient, while the actual yield is the amount of product actually produced in the reaction. The paragraph concludes with an explanation of how to calculate the percent yield using the formula: (actual yield / theoretical yield) * 100%.

05:00
🧮 Calculating Theoretical Yield and Percent Yield for CO2

The second paragraph delves into the specifics of calculating the theoretical yield of CO2 from a given amount of propane (C3H8). It begins with the conversion of 30 grams of propane into moles, using the molar mass of C3H8, which is 44 grams per mole. The molar ratio from C3H8 to CO2, which is 1:3, is then used to find out how many moles of CO2 can be produced from the moles of C3H8. The calculation involves multiplying the moles of C3H8 by the molar ratio and then converting the resulting moles of CO2 back into grams using the molar mass of CO2. The theoretical yield of CO2 is determined to be 90 grams, which is the maximum amount of CO2 that can be produced from 30 grams of propane. With the actual yield given as 70 grams of CO2, the percent yield of the reaction is calculated as 77.8%, indicating the efficiency of the reaction.

Mindmap
Keywords
💡Theoretical Yield
The theoretical yield is the maximum amount of product that can be produced from a chemical reaction, assuming 100% efficiency. It is calculated based on the stoichiometry of the balanced chemical equation and the amount of limiting reactant. In the video, the theoretical yield of CO2 from the combustion of propane (C3H8) is calculated to be 90 grams, assuming complete reaction of 30 grams of propane.
💡Percent Yield
Percent yield is a measure of the actual amount of product obtained from a reaction compared to the theoretical yield. It is calculated by dividing the actual yield by the theoretical yield and then multiplying by 100 to get a percentage. In the context of the video, the percent yield of CO2 is determined to be 77.8%, indicating that 70 grams of CO2 were produced in the experiment, which is 77.8% of the theoretical yield of 90 grams.
💡Combustion Reaction
A combustion reaction is a chemical reaction where a substance reacts with oxygen to produce heat and light, along with carbon dioxide and water as products. In the video, propane (C3H8) is undergoing combustion, reacting with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O).
💡Balanced Chemical Equation
A balanced chemical equation is a representation of a chemical reaction where the number of atoms for each element on the reactant side is equal to the number on the product side, adhering to the law of conservation of mass. In the video, the equation for the combustion of propane is balanced to show that three carbon atoms and eight hydrogen atoms react with five oxygen atoms to produce three carbon dioxide molecules and four water molecules.
💡Limiting Reactant
The limiting reactant is the reactant that is completely consumed in a chemical reaction and determines the maximum amount of product that can be formed. It is crucial in calculating the theoretical yield. In the script, propane is the limiting reactant as it is specified in a fixed amount (30 grams), and the calculation of CO2 production is based on this amount.
💡Actual Yield
The actual yield is the amount of product that is actually produced in a chemical reaction. It is usually less than the theoretical yield due to inefficiencies in the reaction process. In the video, the actual yield of CO2 is given as 70 grams, which is used to calculate the percent yield.
💡Molar Mass
Molar mass is the mass of one mole of a substance, numerically equal to the substance's relative molecular mass or formula weight. It is used to convert between mass and the number of moles of a substance. In the video, the molar mass of propane (C3H8) is 44 grams per mole, which is used to calculate the number of moles from the given mass of propane.
💡Molar Ratio
The molar ratio is the proportion of the amounts of substances reacting in a chemical reaction, usually derived from the balanced chemical equation. It is used to convert moles of one substance to moles of another in a reaction. In the video, the molar ratio of propane to carbon dioxide is 1:3, which is used to find out how many moles of CO2 can be produced from a given number of moles of propane.
💡Stoichiometry
Stoichiometry is the calculation of quantitative aspects in a chemical reaction based on the balanced chemical equation. It allows chemists to determine the amounts of reactants and products in a reaction. In the video, stoichiometry is used to calculate the theoretical yield of CO2 from the combustion of propane.
💡Carbon Dioxide (CO2)
Carbon dioxide is a chemical compound consisting of one carbon atom double-bonded to two oxygen atoms. It is a common product of combustion reactions, as well as a greenhouse gas contributing to global warming. In the video, CO2 is the product of interest, and its yield is calculated from the combustion of propane.
💡Propane (C3H8)
Propane is a three-carbon alkane with the molecular formula C3H8. It is a flammable gas commonly used as a fuel and is the primary component of liquefied petroleum gas (LPG). In the video, propane is the reactant undergoing combustion to produce CO2 and H2O.
Highlights

The video discusses the calculation of theoretical and percent yield of a compound.

A balanced chemical equation is essential for calculating yields, starting with propane (C3H8) and oxygen gas (O2).

Combustion reactions typically produce carbon dioxide (CO2) and water (H2O) as products.

Balancing the chemical equation involves first balancing carbon atoms, then hydrogen, and finally oxygen atoms.

In reactions with two reactants, it's crucial to identify the limiting reactant and the excess reactant.

The limiting reactant is used to calculate theoretical and percent yield, not the excess reactant.

Percent yield is calculated as (actual yield / theoretical yield) * 100%.

Theoretical yield represents the maximum amount of product possible from a reaction at 100% efficiency.

Actual yield is the amount of product actually obtained from the reaction, which is usually less than the theoretical yield.

To calculate the theoretical yield of CO2 from propane, start with the given mass of propane and use molar ratios.

The molar mass of propane (C3H8) is approximately 44 grams per mole.

The molar ratio between propane and carbon dioxide is 1:3.

Converting moles of propane to moles of CO2 involves using the stoichiometry from the balanced equation.

The molar mass of CO2 is also 44 grams per mole, which is used to convert moles back to grams.

The theoretical yield of CO2 from 30 grams of propane is calculated to be 90 grams.

Given the actual yield of CO2 was 70 grams, the percent yield of the reaction is calculated to be 77.8%.

The video provides a step-by-step guide on calculating theoretical and percent yield, emphasizing the importance of understanding chemical equations and molar conversions.

Transcripts

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Chemical ReactionTheoretical YieldPercent YieldCombustionPropaneOxygenCarbon DioxideWaterLimiting ReactantMolar MassMolar RatioEfficiency