Table of Contents
What is the percent yield of the acetyl salicylic acid recovered in the experiment?
When salicylic acid is reacted with the acetic anhydride acetylsalicylic acid and acetic acid are formed. Thus, the percent recovery of acetylsalicylic acid is 75%.
Why is the percentage yield of aspirin low?
One contributing factor for the low yield is that some crystals were lost during the filtration process. There was also a small amount of crystals lost when the crude product was transferred to the new 50 mL Erlenmeyer flask.
How can the percent yield in synthesis of aspirin be increased?
Let the flask cool for a few minutes in air, during which time crystals of aspirin should begin to form. Put the flask in an ice bath to hasten crystallization and increase the yield of product. If crystals are slow to appear, it may be helpful to scratch the inside of the flask with a glass rod.
What was the percent yield of aspirin from this experiment?
Following purification, the calculated mass of the final aspirin product was 2.169 grams. The calculated theoretical yield was 2.520 grams. Thus, the percent error was 13.93 % and the percent yield was 86.07%.
How do you determine percent yield?
- First make sure the both weights have the same units.
- Take your experimental yield and divide it by the theoretical yield.
- Multiply this value by 100 to find the percent yield.
What is a good percent yield?
According to Vogel’s Textbook of Practical Organic Chemistry, yields around 100% are called quantitative, yields above about 90% are called excellent, yields above about 80% very good, yields above about 70% are called good, yields below about 50% are called fair, yields below about 40% are called poor.
What is the purpose of the synthesis of aspirin lab?
Objectives: To synthesize aspirin as economically as possible. To determine the purity and the theoretical and actual % yield, and suggest ways to improve them.
What would happen to your percent yield if the aspirin you prepared was not dried completely?
If the aspirin is not dried completely, the obtained compound will have some water content present and thus the observed weight of the substance would be equal to the weight of aspirin plus the weight of water.
What factors affect the yield of aspirin?
Weighing, mixing, heating, cooling, filtration, washing and drying are processes that can affect the yield and the purity of aspirin. In the chemical reaction, most of the time the aspirin produced might be impure. Therefore, aspirin must go through another process known as recrystallization.
Why is the percentage yield of aspirin less than 100?
Using the theoretical and actual you can calculate percent yield. Your value may vary from the theoretical value for a number of reasons. If it is above 100%, it may be because your aspirin was not completely dried. If it is below 100%, it may be because of sample loss when transferring to the weigh paper.
What factors affect the yield of chemical reactions?
Reactant concentration, the physical state of the reactants, and surface area, temperature, and the presence of a catalyst are the four main factors that affect reaction rate.
How does titration determine purity of aspirin?
1 mole of aspirin will react with 2 moles of NaOH So the number of moles of aspirin must be 0.016/2 = 0.008 moles Molecular mass of aspirin (C9H8O4) = 180, so mass of acetylsalicylic acid = 0.008 * 180 = 1.44 g So % purity of aspirin = (1.44/1.504) * 100 = 95.74% The other titration results was calculated the same way.
What happens when aspirin dissolves in water?
Aspirin is a pain reliever and fever reducer, but if it’s allowed to react with water then it can undergo hydrolysis, forming salicylic acid and acetic acid, which is no longer effective. This reaction can occur under acidic or basic conditions.
What is a theoretical yield of aspirin?
Conclusion: A total of 2.169 grams of pure aspirin was synthesize out of a possible yield of 2.52 grams. Thus, there was 86.07% product yield. Acetylation of salicylic acid makes aspirin less acidic and therefore less damaging to the digestive system of the human body.
What is a percent yield in chemistry?
The percent yield is the ratio of the actual yield to the theoretical yield, expressed as a percentage: Percent Yield=Actual YieldTheoretical Yield×100% Percent yield is very important in the manufacture of products.
Why is it important to calculate the percent yield in a chemical reaction?
It is important to calculate the percent yield in a chemical reaction because it shows the efficiency of a chemical reaction. Percentage yield is calculated to compare the actual yield quantity of a product. This help us to identify whether all of the reactants are converted with no loss or waste.
How do you find the percent yield of a titration?
To determine percent yield, divide the actual yield by the theoretical yield and multiply by 100. For this example, use the equation: 82 grams of silver / 85 grams of silver x 100 = 96 percent.
What does the percent yield tell you about your results?
Percent yield will indicate how much product is left-over and help you formulate a plan to create less waste during the chemical reactions.
What does a high percent yield indicate?
A higher percent yield might signal that your product is being contaminated by water, excess reactant, or another substances. A lower percent yield might signal that you mis-measured a reactant or spilled a portion of your product.
What does percent yield say?
The percent yield is the ratio of the actual yield to the theoretical yield, expressed as a percentage. Percent yield is very important in the manufacture of products. Much time and money is spent improving the percent yield for chemical production.
What type of reaction is the production of aspirin?
The synthesis of aspirin is known in organic chemistry as an esterification reaction. This is a substitution reaction in which an alcohol (the –OH group in salicylic acid) reacts with acetic anhydride to form an ester, aspirin.
Why is the purity of aspirin important?
It is important to ensure that the purified product is actually Aspirin. This is because if it is not Aspirin, then testing the purity of it will become useless. It is possible for the Aspirin to be converted back into salicylic acid due to hydrolysis.
What is the purpose of adding cold water in the synthesis of aspirin?
The ice has another role to play. Aspirin is only slightly soluble in water so if you add it to the reaction mixture the product would rather clump together than be in the water phase. This causes the solid to begin to form or ‘precipitate’.
What could cause a less than 100% yield?
Usually, percent yield is lower than 100% because the actual yield is often less than the theoretical value. Reasons for this can include incomplete or competing reactions and loss of sample during recovery.