You extract the iron from a tablet and dilute that to 350.0 ml in a volumetric flask. You transfer 0.500 ml of this solution to a 75.0 ml volumetric flask and dilute this to volume. When you measure the concentration of this solution, you find that it is 1.87 ppm Fe. How many milligrams of Fe were in the tablet?
Fe sample ==> 350 mL.
0.50 mL ==> 75 mL = 1.87 ppm
1.87 ppm = 1.87 mg/L
How much Fe is in the 75 mL? That's 1.87 mg/L x 0.075 mL = 0.140 mg.
Therefore, the 0.5 mL must have cntained 0.140 mg Fe. Where did that come from? That 0.5 mL came from the 350 mL so there must have been 0.140 x (350/0.4) = ? mg Fe in the original sample.
Where did the 0.4 come from in your final calculation? Also your 0.075 should be L, not mL...
To find the number of milligrams of Fe in the tablet, we need to perform the following calculations step by step:
Step 1: Calculate the dilution factor
The dilution factor is the ratio of the final volume to the initial volume. In this case, we diluted the iron solution from 350.0 ml to 0.500 ml. The dilution factor can be calculated as:
Dilution factor = Final volume / Initial volume
Dilution factor = 0.500 ml / 350.0 ml
Step 2: Calculate the concentration of the original iron solution
The concentration of the original iron solution can be calculated using the dilution factor and the measured concentration of the final solution. Since the concentration is expressed in parts per million (ppm), we need to convert it to milligrams per liter (mg/L):
Concentration (mg/L) = Concentration (ppm) * Dilution factor
Step 3: Calculate the mass of iron in 350.0 ml of the original solution
To find the mass of iron in the original solution, we need to multiply the concentration (in mg/L) by the volume (in liters):
Mass of Fe = Concentration (mg/L) * Volume (L)
Finally, let's perform the calculations:
Step 1:
Dilution factor = 0.500 ml / 350.0 ml
Dilution factor = 0.00143 (rounded to 5 decimal places)
Step 2:
Concentration (mg/L) = 1.87 ppm Fe * 0.00143
Concentration (mg/L) = 0.0026701
Step 3:
Mass of Fe = 0.0026701 mg/L * 0.350 L
Mass of Fe = 0.0009345 mg
Therefore, there were approximately 0.0009345 mg of Fe in the tablet.
To calculate the number of milligrams of Fe (iron) in the tablet, we need to follow the given procedure:
Step 1: Calculate the concentration of iron in the diluted solution.
Given:
- Volume of the diluted solution = 75.0 ml
- Concentration of the diluted solution = 1.87 ppm Fe (parts per million)
To convert parts per million (ppm) to milligrams per liter (mg/L), we can use the following conversion factor:
1 ppm = 1 mg/L
So, the concentration of the diluted solution in mg/L is also 1.87 mg/L.
Step 2: Calculate the volume of the undiluted solution.
Given:
- Volume of the diluted solution = 75.0 ml
- Dilution factor = (Volume of the undiluted solution / Volume of the diluted solution)
The dilution factor can be calculated as:
Dilution factor = (Volume of the undiluted solution / Volume of the diluted solution) = (350.0 ml / 0.500 ml)
Step 3: Calculate the concentration of iron in the undiluted solution.
We know that the concentration of the diluted solution is 1.87 mg/L, and the dilution factor is calculated as (Volume of the undiluted solution / Volume of the diluted solution). Therefore, we can write the relationship as:
Concentration of the undiluted solution = Concentration of the diluted solution * Dilution factor
Concentration of the undiluted solution = 1.87 mg/L * (350.0 ml / 0.500 ml)
Step 4: Calculate the number of milligrams of Fe in the tablet.
Given:
- Volume of the undiluted solution = 350.0 ml
- Concentration of the undiluted solution = calculated in step 3
The number of milligrams of Fe in the tablet can be calculated as:
Milligrams of Fe = Concentration of the undiluted solution * Volume of the undiluted solution
Now, you can substitute the values in the formula and calculate the result.