<u>Answer:</u> The percent yield of the aspirin is 77.5 %.
<u>Explanation:</u>
To calculate the mass of acetic anhydride, we use the equation:
![\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}](https://tex.z-dn.net/?f=%5Ctext%7BDensity%20of%20substance%7D%3D%5Cfrac%7B%5Ctext%7BMass%20of%20substance%7D%7D%7B%5Ctext%7BVolume%20of%20substance%7D%7D)
Density of acetic anhydride = 1.08 g/mL
Volume of acetic anhydride = 2.80 mL
Putting values in above equation, we get:
![1.08g/mL=\frac{\text{Mass of acetic anhydride}}{2.80mL}\\\\\text{Mass of acetic anhydride}=(1.08g/mL\times 2.80mL)=3.024g](https://tex.z-dn.net/?f=1.08g%2FmL%3D%5Cfrac%7B%5Ctext%7BMass%20of%20acetic%20anhydride%7D%7D%7B2.80mL%7D%5C%5C%5C%5C%5Ctext%7BMass%20of%20acetic%20anhydride%7D%3D%281.08g%2FmL%5Ctimes%202.80mL%29%3D3.024g)
To calculate the number of moles, we use the equation:
.....(1)
- <u>For acetic anhydride:</u>
Given mass of acetic anhydride = 3.024 g
Molar mass of acetic anhydride = 102.1 g/mol
Putting values in equation 1, we get:
![\text{Moles of acetic anhydride}=\frac{3.024g}{102.1g/mol}=0.0296mol](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20acetic%20anhydride%7D%3D%5Cfrac%7B3.024g%7D%7B102.1g%2Fmol%7D%3D0.0296mol)
- <u>For salicylic acid:</u>
Given mass of salicylic acid = 1.24 g
Molar mass of salicylic acid = 138.12 g/mol
Putting values in equation 1, we get:
![\text{Moles of salicylic acid}=\frac{1.24g}{138.12g/mol}=0.0089mol](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20salicylic%20acid%7D%3D%5Cfrac%7B1.24g%7D%7B138.12g%2Fmol%7D%3D0.0089mol)
The chemical equation for the combustion of hexane follows:
![C_4H_6O_3+C_7H_6O_3\rightarrow C_9H_8O_4+C_2H_4O_2](https://tex.z-dn.net/?f=C_4H_6O_3%2BC_7H_6O_3%5Crightarrow%20C_9H_8O_4%2BC_2H_4O_2)
By Stoichiometry of the reaction:
1 mole of salicylic acid reacts with 1 mole of acetic anhydride
So, 0.0089 moles of salicylic acid will react with =
of acetic anhydride
As, given amount of acetic anhydride is more than the required amount. So, it is considered as an excess reagent.
Thus, salicylic acid is considered as a limiting reagent because it limits the formation of product.
By Stoichiometry of the reaction:
1 mole of salicylic acid produces 1 mole of aspirin
So, 0.0089 moles of salicylic acid will produce =
of aspirin
Now, calculating the mass of aspirin from equation 1, we get:
Molar mass of aspirin = 180.16 g/mol
Moles of aspirin = 0.0089 moles
Putting values in equation 1, we get:
![0.0089mol=\frac{\text{Mass of aspirin}}{180.16g/mol}\\\\\text{Mass of aspirin}=(0.0089mol\times 180.16g/mol)=1.60g](https://tex.z-dn.net/?f=0.0089mol%3D%5Cfrac%7B%5Ctext%7BMass%20of%20aspirin%7D%7D%7B180.16g%2Fmol%7D%5C%5C%5C%5C%5Ctext%7BMass%20of%20aspirin%7D%3D%280.0089mol%5Ctimes%20180.16g%2Fmol%29%3D1.60g)
- To calculate the percentage yield of aspirin, we use the equation:
![\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100](https://tex.z-dn.net/?f=%5C%25%5Ctext%7B%20yield%7D%3D%5Cfrac%7B%5Ctext%7BExperimental%20yield%7D%7D%7B%5Ctext%7BTheoretical%20yield%7D%7D%5Ctimes%20100)
Experimental yield of aspirin = 1.24 g
Theoretical yield of aspirin = 1.60 g
Putting values in above equation, we get:
![\%\text{ yield of aspirin}=\frac{1.24g}{1.60g}\times 100\\\\\% \text{yield of aspirin}=77.5\%](https://tex.z-dn.net/?f=%5C%25%5Ctext%7B%20yield%20of%20aspirin%7D%3D%5Cfrac%7B1.24g%7D%7B1.60g%7D%5Ctimes%20100%5C%5C%5C%5C%5C%25%20%5Ctext%7Byield%20of%20aspirin%7D%3D77.5%5C%25)
Hence, the percent yield of the aspirin is 77.5 %.