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The Role of theoretical yield and percent yield in chemistry

Chemistry is unique in two features. One is a chemistry lab and the other is chemical reactions. In daily routine, most of the things revolve around two vital points. One is input and the other is output. What we have invested comes to us. It depends on whether it comes in profit or loss! Similarly, […]

organic chemistry

Chemistry is unique in two features. One is a chemistry lab and the other is chemical reactions. In daily routine, most of the things revolve around two vital points. One is input and the other is output. What we have invested comes to us. It depends on whether it comes in profit or loss! Similarly, during a chemical reaction, the products which we have obtained are called yield. Yield is the product of the input (reactants). It is classified into two categories.

• Theoretical yield

• Actual yield

Theoretical yield

Theoretical yield is nothing but the result of the expected product. It is the number of products or output which we have expected at the start of the reaction. Theoretical yield is an ideal yield and it cannot be achieved. Because it involves the continuation of reaction under ideal conditions such as: 

  • Reactant would be pure and have no impurities.
  • There will be no loss in products or we get the exact yield according to reactants.
  • No by-products will come along with the actual product.

All these conditions are ideal and show a hundred percent efficiency. These conditions cannot be achieved under normal circumstances. That’s why it is difficult to obtain theoretical yield. Furthermore, it is very difficult to calculate the theoretical yield on paper. It involves a basic process in calculating which involves: 

  • the chemical equation must be balanced.
  • Before deriving theoretical yield, it is important to calculate the mole ratio between reactants and products.

But you can remain in a safe zone and avoid all possible errors by just putting the values in a bar and calculate it by a theoretical yield calculator.

Actual yield

it is the actual yield that we have obtained in a chemical reaction. It is not an ideal yield but the actual amount of products which are obtained under normal conditions. It is always less than the theoretical yield. Actual yield is not fanaticized but it is the result according to the efficiency of reactants.

Percent yield

After deriving the products it is necessary to calculate the yield on paper so that it can be estimated how much actual product is obtained from the reactants. How many by-products come, and how many reactants are wasted or precipitated? It is executed by comparing the values of both yields. 

I.e. dividing actual yield by theoretical yield and Multiply it by 100. Percent yield does not contain a 100% yield. It is lower than 100 percent. It is because the actual yield is less than the theoretical yield.

Percent yield = (Actual yield/percent yield)*100

To understand this, let’s consider an example. In a chemical reaction of calcium carbonate, the compound splits into calcium oxide and carbon dioxide. The theoretical yield which we have calculated is 34.5 g carbon dioxide whereas the actual yield which we have obtained from the reaction is 27g carbon dioxide. Hence we will calculate the percent yield by putting it into the formula. I.e. 

27/34.5= 0.78 grams

0.78 * 100= 78% yield

According to the result, we will obtain a 78 percent yield in the process. But if you want to solve the question without being into the trouble of calculation. You can completely skip this part and just put the values and calculate by percent yield calculator. It will derive an accurate percentage of yield obtained.

Thus theoretical yield and actual yield both possess a significant space in chemistry. Without calculating them, one cannot assume the output. And it would become impossible to evaluate the efficiency of reactants without calculating yield.

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