Question

Freon-12, CCl₂F₂, is prepared from CCl₄ by reaction with HF. The other product of this reaction is HCl. Outline the steps needed to determine the percent yield of a reaction that produces 12.5 g of CCl₂F₂ from 32.9 g of CCl₄. Freon-12 has been banned and is no longer used as a refrigerant because it catalyzes the decomposition of ozone and has a very long lifetime in the atmosphere. Determine the percent yield.

a) Calculate the theoretical yield.
b) Calculate the percent yield using the formula: (Actual Yield/Theoretical Yield) × 100.
c) Determine the molar mass of CCl₂F₂.
d) Balance the chemical equation for the reaction.

Answer 1

To calculate the percent yield of producing Freon-12 from carbon tetrachloride, first balance the chemical reaction, find the molar mass of CCl₂F₂, calculate the theoretical yield in grams and then apply the percent yield formula with the actual yield given as 12.5 g.

Step-by-step explanation:

The question is asking how to calculate the percent yield of a chemical reaction that produces Freon-12 (CCl₂F₂) from carbon tetrachloride (CCl₄) using hydrofluoric acid (HF). To determine the percent yield, follow these steps:

1. 
   
3. Balance the chemical equation: CCl₄ + 2HF → CF₂Cl₂ + 2HCl.
4. 
   
6. Determine the molar mass of CCl₂F₂ to be 120.91 g/mol using the periodic table values for Cl (35.45 g/mol), C (12.01 g/mol), and F (19.00 g/mol).
7. 
   
9. Calculate the moles of CCl₄ used based on the provided mass (32.9 g) and its molar mass (153.82 g/mol).
10. 
    
12. Identify the mole ratio from the balanced equation (1 mole CCl₄ : 1 mole CF₂Cl₂).
13. 
    
15. Convert the moles of CCl₄ to moles of CF₂Cl₂ using the mole ratio.
16. 
    
18. Determine the theoretical yield in grams by multiplying the moles of CF₂Cl₂ by its molar mass.
19. 
    
21. Finally, calculate the percent yield by using the formula: (Actual Yield/Theoretical Yield) × 100. For this question, the actual yield is 12.5 g.