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Theoretical Yield Definition
It is the amount of product obtained when the whole of the limiting reactant used in a reaction is completely converted into the products without any loss of reactants. It is the product of a perfect chemical reaction.
Limiting reactant
It is the reactant that decides the amount of product obtained. It helps in increasing the yield of a reaction. If you know which is reactant is limiting, you would use only the required amount of other reactants. For example, you have 47 buns and 24 patties. You can make on only 23 sandwiches although you are left with one extra patty. The limiting reactant in this process is buns.
Excess reactant
It is the reactant of which some quantity is left by the end of the reaction. In the above-mentioned example, the excess reactant is patties.
Why called “theoretical”?
Theoretical means involving theory. It is the calculated product without performing any experiment. No laboratory reaction is a perfect chemical reaction. It is not possible to convert all of the reactants completely into the required product without producing any by-products or preventing any side reaction to take place.
How to calculate theoretical yield?
Most of the time we are asked to find the theoretical yield from actual and percentage yield. If you use our Theoretical Yield Calculator, you can easily calculate the theoretical yield. All you have to know is the percentage yield and actual yield.
Actual yield
It is the amount of product obtained when the reaction is actually performed. In the laboratory, it is the amount of product that is formed in your beaker, after it is purified and dried.
The actual yield can easily be calculated by this formula;
\(\text{Actual yield} = \dfrac{\text{percentage yield} \times \text{theoretical yield}}{100}\)
It is mostly present on the left side of a chemical reaction.
Percentage Yield:
It is the ratio of actual yield to the theoretical yield multiplied by 100. It is 100 percent for a reaction whose actual and theoretical yield is the same. The percentage yield can be more than 100 percent. It is because more than the predicted amount of reactant is recovered during the reaction.
Method 1
\(\text{Percentage yield} = \dfrac{\text{Autual yeld}}{\text{Theoratical yield}} \times 100\)
Method 2
\(\text{percentage yield} = \dfrac{m_B \times M_A}{m_A \times M_B} \times 100\)
where
- \(m_A\) is the mass of first substance A in grams.
- \(m_B\) is the mass of the second substance B in grams.
- \(M_A\) is the molar mass of first substance A in grams per mole.
- \(M_B\) is the molar mass of second substance B in grams per mole.
Method 3
\( \text{percentage yield} = \dfrac{\text{moles of product B}}{\text{moles of product A}} \times 100\)
Where
mole is equal to mass over the molar mass.
How to use our Theoretical Yield Calculator?
Enter the percentage yield and actual yield found by using the formulas written above in their respective sections and click calculate. Simple as that!