To determine the yield of your ASA synthesis, you can quantify the amount of unreacted SA
Weigh out 0.15 g of your crude ASA into a clean tared 7 mL vial. Record exact mass.
2) Add 5 mL ethanol.
3) Cap vial and mix well.
4) Transfer the above solution into a 50 mL volumetric flask using a transfer pipette.
5) Use wash bottle to thoroughly rinse vial multiple times, transferring each rinse into the volumetric flask
6) Bring flask volume to the 50.00 mL mark with D.I. water.
7) Place 1.00 mL of this solution into a clean, dry 7 mL vial. Add 3.00 mL 0.025 M Fe(NO3)3. Cap and mix well.
8) Fill cuvette 2/3 to 3/4 full with the solution from step 7).
9) Read the absorbance at 517 nm.
10) Determine the mass of SA in the crude analyzed and then the percentage of ASA (ASA yield) in the crude. ϵ = 2147 M-1cm-1 of the iron-salicylate complex, SA-Fe(H2O)4+.
MM of ASA= 180.16 g/mol
MM SA= 138.12 g/mol
My absorbance= .141
So far all I have is (using beers law)
.141= 2141 M-1 cm-1(1)(c)
c= .141/2141= .000065673 M
.000065673 * 50 mL= .0032836516 moles SA?
I am very lost, any and all help would be great! Please and thank you!
I think you meant to type in 2147. Your M is ok. However, mols = M x L (not mL) so 6.567E-5 x 0.05 = 3.284E-6 and that times molar mass SA gives grams SA in the 0.15g sample. If you subtract 0.15 - grams SA that gives you grams ASA and percent yield is (g ASA/0.15)*100 = ?
Thank you!
To determine the yield of your ASA synthesis, you can quantify the amount of unreacted SA. In order to do that, you need to follow the steps given and use Beer's law to calculate the concentration of SA in the solution.
Let's go step by step:
1) Weigh out 0.15 g of your crude ASA into a clean tared 7 mL vial. Record the exact mass.
- You have correctly done this step.
2) Add 5 mL ethanol.
- By adding ethanol, you are dissolving your crude ASA in the solvent.
3) Cap the vial and mix well.
4) Transfer the above solution into a 50 mL volumetric flask using a transfer pipette.
- This step is done to dilute the solution to a known volume.
5) Use a wash bottle to thoroughly rinse the vial multiple times, transferring each rinse into the volumetric flask.
- By rinsing the vial, you are making sure that all the remaining ASA is transferred to the volumetric flask.
6) Bring the volume of the flask to the 50.00 mL mark with deionized (D.I.) water.
- You are adding water to reach the desired volume of 50 mL.
7) Place 1.00 mL of this solution into a clean, dry 7 mL vial. Add 3.00 mL of 0.025 M Fe(NO3)3. Cap and mix well.
- This step involves the reaction between SA and Fe(NO3)3 to form the iron-salicylate complex, SA-Fe(H2O)4+.
8) Fill a cuvette 2/3 to 3/4 full with the solution from step 7).
9) Read the absorbance at 517 nm.
- The absorbance measurement provides information about the concentration of the iron-salicylate complex in the solution.
10) Determine the mass of SA in the crude analyzed and then the percentage of ASA (ASA yield) in the crude.
Now, let's calculate the concentration of SA in the solution using Beer's law:
- Beer's law equation: A = εlc
where A is the absorbance, ε is the molar absorptivity (given as 2147 M-1cm-1 for the iron-salicylate complex), l is the path length (usually 1 cm), and c is the concentration.
Given: A = 0.141, ε = 2147 M-1cm-1, l = 1 cm
Substituting the given values into the equation:
0.141 = 2147 M-1cm-1 * 1 cm * c
c = 0.141 / 2147 M-1cm-1 = 6.5673 x 10^-5 M
Since you transferred the solution from the 50 mL volumetric flask, the concentration is calculated as follows:
Concentration of SA = (6.5673 x 10^-5 M) * (50 mL / 1000 mL) = 3.28365 x 10^-6 moles SA
Now, to determine the mass of SA in the crude analyzed, we can use the molar mass of SA (138.12 g/mol):
Mass of SA = concentration of SA * molar mass SA
Mass of SA = (3.28365 x 10^-6 moles SA) * (138.12 g/mol) = 4.53 x 10^-4 g
Finally, to calculate the percentage of ASA (ASA yield) in the crude:
ASA yield = (mass of ASA / mass of crude ASA) * 100%
ASA yield = (0.15 g / 4.53 x 10^-4 g) * 100% ≈ 33.1%
Therefore, the yield of ASA in the crude is approximately 33.1%.
Note: Please double-check the calculations and units to ensure accuracy.