Question

Calculate the theoretical yield of benzil assuming you begin with 2.72 grams of benzoin.

Answer 1

Answer : The correct answer for theoretical yield = 2.73 g

Theoretical yield : It is defined as maximum amount of yield that is expected to be produce from reactants . The theoretical yield is decided by amount of product formed by Limiting Reagent .

Theoretical yield can be calculated bu using stroichiometric relation between mole of limiting reactant and product .

The reaction of Benzil can be written as :

one mole of Benzoin produces one mole of Benzil ( Image ) .

Since only one reactant , Benzoin is present so limiting reactant can be considered as Benzoin .

Theoretical yield can be calculates in following steps :

Step 1 : Conversion of mass of Benzoin to its mole .

Mass can be converted to mole using following formula :

`Mole = (Mass (g))/(Molar mass (g)/(1 mol))`

Molar mass of Benzoin (C₁₄H₁₂O₂ ) = 212.24
`(g)/(mol)`

Plugging value of Mass and molar in mole formula :

`Mole = (2.72 g)/(212.24 (g)/(mol))`

Mole = 0.013 mol

Step 2 : To find mole ratio of Benzil to Benzoin .

Mole ratio can be find out from balanced reaction . From balanced reaction one mole of Benzoin giving one mole of Benzil , Hence mole ratio = 1 : 1

Step 3 : Find mole of Benzil

`Mole of Benzil = 0.013 mol of Benzoin * (1 mole of Benzil )/(1 mole of Benzoin)`

Mole of Benzil = 0.013 mol

Step 4 : To find mass of Benzil

Molar mass of Benzil (C₁₄H₁₀O₂ ) = 210.232
`(g)/(mol)`

Plugging value in mole formula

`0.013 mole of Benzil = (mass of Benzil )/(210.232 (g)/(mol))`

Multiplying both side by 210.232
`(g)/(mol)`

`0.013 mol * 210.232 (g)/(mol) = (mass of benzil)/(210.232 (g)/(mol)) * 210.232 (g)/(mol)`

Mass of Benzil = 2.73 g

Hence Theoretical mass of Benzil = 2.73 g