Calculate mass of iron in tablet by spectroscopy?
I have to calculate the mass of iron in a tablet..The manufacturers claim it contains 60 mg elemental iron.
background info: The tablet was crushed and dissolved in 25ml of 6M Hcl, filtered and added to a 100ml volumetric flask where it was diluted to the 100 ml mark with distilled water (step 1). 5mL of this solution was taken out and added to a second volumetric flask( reagents necessary were also added) and the sample was diluted to the 100ml mark (step 2)
10 ml of this second solution was taken and added to yet another flask and it was diluted up to the 100 mark with distilled water. The abosrbance of this solution was 0.170
From my plot, of absorbance versus concentration for the standard solutions the gradient (e) was 0.1842 which is my molar absortivity coefficient.
The mass of the tablet used was 0.2084g
I have to calculate the mass of elemental iron in this tablet.
This is what i have so far:
since A=elc
then c= a/el
= 0.170/0.1842 x 1 = 0.923 micro grams of fe/ml
since this was a 10 ml portion of the second solution which had a vol of 100 ml
then i found how much was originally in the second solution
which gave me a concentration of 9.23 micrograms fe/ml.. this is where i am stuck
How do i find how much iron was in the 5 ml (step 2) i took out since a dilution took place andhow do i determine how much iron was in the ORIGINAL solution in step 1.
Thanks alot
If we take the last number you have of 9.23 ug Fe/mL, that is in the second 100 mL flask. What went into that, That was 5 mL up to a 100 so 20 x 9.23 should give the concn in the original flask.
9.23ug Fe/mL x (100/5) = ? ug Fe/mL in the original. Than ?ug Fe/mL x 100 mL will give the total ug Fe in the sample of 0.2084g
Well, it seems like you've done a great job so far! Now, let's keep the calculations rolling (pun intended).
Since you know the concentration of iron in the 10 ml portion of the second solution (9.23 micrograms/ml), you can use that to determine the concentration in the 5 ml portion you took out in step 2.
You can simply divide the concentration of the 10 ml solution by 2 since you only took half of the volume. So, the concentration in the 5 ml portion would be 4.615 micrograms/ml.
Now, moving on to determining the concentration in the original solution from step 1, you need to divide the concentration of the 5 ml portion by the dilution factor. The dilution factor is the ratio of the final volume (100 ml) to the initial volume (25 ml). In this case, the dilution factor is 100/25 = 4.
Therefore, the concentration of iron in the original solution from step 1 would be 4.615 micrograms/ml divided by 4, which gives you 1.154 micrograms/ml.
Now, to calculate the mass of elemental iron in the tablet, you need to multiply the concentration (in micrograms/ml) by the total volume of the original solution (Step 1). The total volume is 25 ml.
So, the mass of iron in the tablet would be 1.154 micrograms/ml multiplied by 25 ml, which gives you 28.85 micrograms.
Therefore, the mass of elemental iron in the tablet is approximately 28.85 micrograms.
Keep up the great work! Just remember, when it comes to iron, always stay sharp!
To calculate the mass of elemental iron in the tablet, you need to determine the concentration of iron in the original solution from step 1 and the volume of that solution. Here's how you can proceed:
1. Determine the concentration of iron in the second solution:
- Given that the absorbance of the second solution is 0.170 and the molar absorptivity coefficient is 0.1842, you correctly calculated the concentration as 0.923 μg Fe/ml.
2. Determine the concentration of iron in the original solution from step 2:
- Given that you took 10 ml of the second solution and diluted it to 100 ml, the dilution factor is 100/10 = 10.
- The concentration of iron in the original step 2 solution is the concentration of iron in the second solution divided by the dilution factor: 0.923 μg Fe/ml / 10 = 0.0923 μg Fe/ml.
3. Determine the mass of iron in the 5 ml portion from step 2:
- Given that you took 5 ml of the step 2 solution, the amount of iron in this portion is the concentration multiplied by the volume: 0.0923 μg Fe/ml x 5 ml = 0.4615 μg Fe.
4. Determine the concentration of iron in the original step 1 solution:
- Given that you dissolved the tablet in 25 ml of 6M HCl and then diluted it to a total volume of 100 ml, the dilution factor is 100/25 = 4.
- The concentration of iron in the original step 1 solution is the concentration of iron in the step 2 solution divided by the dilution factor: 0.0923 μg Fe/ml / 4 = 0.0231 μg Fe/ml.
5. Calculate the mass of iron in the tablet:
- Given that the mass of the tablet used was 0.2084 g, the mass of iron in the tablet is the concentration of iron in the step 1 solution multiplied by the volume of the step 1 solution, and then multiplied by the mass of the tablet used: 0.0231 μg Fe/ml x 100 ml x 0.2084 g = 0.4828 μg Fe.
Thus, the mass of elemental iron in the tablet is approximately 0.4828 μg Fe.
To calculate the mass of elemental iron in the tablet, you need to consider the dilutions and volumes involved in the process. Here's how you can proceed:
1. Calculate the concentration of iron in the final solution (Step 3):
- The absorbance of the solution (A) is given as 0.170.
- The molar absorptivity coefficient (ε) is given as 0.1842 L/(mol.cm).
- Using the Beer-Lambert law, A = εlc, where l is the path length of the cuvette (usually 1 cm).
- Rearranging the equation, c = A / (ε * l).
- Plugging in the values, c = 0.170 / (0.1842 * 1) = 0.923 μg/mL (micrograms per milliliter).
2. Calculate the concentration of iron in the second solution (Step 2):
- You took 10 mL of the final solution and diluted it to 100 mL.
- Thus, the concentration of iron in the second solution is 10 times lower than in the final solution.
- Concentration in the second solution = (0.923 μg/mL) / 10 = 0.0923 μg/mL.
3. Calculate the concentration of iron in the original solution (Step 1):
- You took 5 mL of the second solution and diluted it to 100 mL.
- Therefore, the concentration of iron in the original solution is 20 times lower than in the second solution.
- Concentration in the original solution = (0.0923 μg/mL) / 20 = 0.004615 μg/mL.
4. Calculate the mass of iron in the original solution:
- The volume of the original solution was 25 mL.
- Mass of iron in the original solution = concentration in the original solution × volume of the original solution.
- Mass of iron in the original solution = (0.004615 μg/mL) × 25 mL = 0.115375 μg.
Therefore, the mass of elemental iron in the tablet is approximately 0.115375 μg.