Chlorobenzene (C6HsCl) is used in the production of many important chemicals, such as
aspirin, dyes, and disinfectants. One industrial method of preparing chlorobenzene is to
react benzene (C6H6) with chlorine and a by-product is hydrogen chloride. If 72 grams of
benzene reacts with 98 grams of chlorine, and in the lab, 94 grams of chlorobenzene was Produced
To calculate the theoretical yield of chlorobenzene, we need to determine which reactant is limiting and use its stoichiometry to calculate the maximum amount of product that can be formed.
1. Calculate the moles of benzene:
Molar mass of benzene (C6H6) = 6*12.01 + 6*1.01 = 78.11 g/mol
Moles of benzene = Mass of benzene / Molar mass of benzene = 72 g / 78.11 g/mol
2. Calculate the moles of chlorine:
Molar mass of chlorine = 35.45 g/mol
Moles of chlorine = Mass of chlorine / Molar mass of chlorine = 98 g / 35.45 g/mol
3. Use the moles of benzene and chlorine to determine the limiting reactant:
The balanced chemical equation for the reaction is:
C6H6 + Cl2 → C6H5Cl + HCl
From the equation, we can see that the mole ratio of benzene to chlorine is 1:1. Therefore, the limiting reactant is the one with fewer moles, which is benzene in this case.
4. Calculate the theoretical yield of chlorobenzene:
From the balanced equation, we can see that the mole ratio of benzene to chlorobenzene is also 1:1. Therefore, the moles of chlorobenzene will be equal to the moles of benzene.
Moles of chlorobenzene = Moles of benzene
5. Calculate the mass of chlorobenzene:
Molar mass of chlorobenzene (C6H5Cl) = 6*12.01 + 1*1.01 + 1*35.45 = 112.56 g/mol
Mass of chlorobenzene = Moles of chlorobenzene * Molar mass of chlorobenzene = Moles of benzene * 112.56 g/mol
6. Calculate the actual yield of chlorobenzene:
Actual yield = 94 g
The actual yield of chlorobenzene is given as 94 grams. Comparing this to the theoretical yield, we can determine the percent yield:
Percent yield = (Actual yield / Theoretical yield) * 100 = (94 g / (Moles of benzene * 112.56 g/mol)) * 100
Note: To calculate the percent yield, you need the moles of benzene, which was calculated in Step 1. Plug in the values to calculate the percent yield of chlorobenzene.