Calculating Salicylic Acid Required for Aspirin Production: A Guide

In summary, to prepare 45.0g of aspirin with a yield of 85%, one must use a theoretical yield of approximately 53g of salicylic acid. This can be calculated by dividing 45g by 0.85 and using the molar ratio of salicylic acid to aspirin to determine the needed amount.
  • #1
Larrytsai
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Aspirin, C9 H8 O4 (molar mass 180.2g/mol), a drug used to relieve minor aches and pains, is prepared by the following reaction:

C7 H6 O3 (s) + C4 H6 O3 (l) --> C9 H8 O4 (s) + C2 H4 O2 (l)

If you need to prepare 45.0g of aspirin, and yield for the reaction is 85% how many grams of salicylic acid, C7 H6 O3 (molar mass 138.1g/mol) must you use?

i was wondering where to start? like I am really confused with that 85% thing too
 
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  • #2
The description and question mean 45 grams of aspirin is 85 percent of what would result if all of the salicylic acid were to become apirin.
 
  • #3
(45 g/ theoretical yield) x 100 = 85%
 
  • #4
Divide 45g by 85% (expressed as 0.85) to get the theoretical yield.
Solve for the amount of salicylic acid using the relationship of moles of aspirin produced (theoretical) from salicylate used.
Or, you could ask yourself, "How many moles of salicylate would yield 'X' moles (theoretical yield) of aspirin?"
 

1. How do I calculate the amount of salicylic acid needed for aspirin production?

The amount of salicylic acid required for aspirin production can be calculated by multiplying the desired amount of aspirin by the molecular weight of salicylic acid and dividing by the molecular weight of aspirin. This will give you the amount of salicylic acid needed in moles, which can then be converted to grams using the molar mass of salicylic acid.

2. Can I use any type of salicylic acid for aspirin production?

It is recommended to use pure, reagent-grade salicylic acid for aspirin production. Impure forms may affect the yield and purity of the final product. It is also important to ensure that the salicylic acid used does not contain any contaminants that could be harmful if consumed.

3. How do I know if I have added enough salicylic acid for aspirin production?

The amount of salicylic acid needed for aspirin production will depend on the specific reaction conditions and desired yield. It is important to carefully follow the instructions and measurements in the procedure to ensure the correct amount is added. You can also use analytical techniques, such as titration, to confirm the amount of salicylic acid present in the reaction mixture.

4. Can I use a different acid instead of salicylic acid for aspirin production?

No, salicylic acid is the key ingredient in aspirin production and cannot be substituted with other acids. It is chemically necessary for the reaction to occur and produce aspirin. Using a different acid may result in a different product or may not produce any product at all.

5. Is it necessary to calculate the amount of salicylic acid for every batch of aspirin produced?

Yes, it is important to calculate the amount of salicylic acid needed for each batch of aspirin as the reaction conditions and desired yield may vary. Additionally, the amount of salicylic acid needed may also change if there are any changes in the reaction procedure or equipment used. It is important to ensure accuracy and consistency in the production of aspirin.

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