Question

CLEAN-UP * Discard any of the remaining green solid into the blue waste baskets near the balances. * Clean and rinse all glassware well with tap water, including the test tubes. * Return the test tubes to the test tube racks. * Return your glassware to the labelled locations. Make sure the rubber stoppers are placed on or nearby the volumetric flasks. The glassware does not need to be completely dry. CALCULATIONS & QUESTIONS 1. Use the given value for the concentration of iron in the stock solution and the volume you used to calculate the concentration of iron(II) ions (Fe2+) in mg/L in the blank and each of the three standard solutions. 2. Present the concentration of iron(II) ions (Fe2+) in mg/L and absorbance of the blank and standards in a table for graphing. 3. Construct a calibration graph from the above values and draw the best-fitting straight line through the data points. Determine the concentration of iron with its unit in the diluted unknown solution on the calibration graph. 4. From the diluted unknown concentration, calculate the concentration of iron in the original unknown solution. 5. Calculate the mass of iron in the solid unknown sample. 6. Calculate the percentage of iron in the unknown sample where: % iron in unknown sample = (mass of iron in unknown sample / total mass of unknown sample) X 100%

          CLEAN-UP

* Discard any of the remaining green solid into the blue waste baskets near the balances.
* Clean and rinse all glassware well with tap water, including the test tubes.
* Return the test tubes to the test tube racks.
* Return your glassware to the labelled locations. Make sure the rubber stoppers are placed on or nearby the volumetric flasks. The glassware does not need to be completely dry.

CALCULATIONS & QUESTIONS
1. Use the given value for the concentration of iron in the stock solution and the volume you used to calculate the concentration of iron(II) ions (Fe2+) in mg/L in the blank and each of the three standard solutions.
2. Present the concentration of iron(II) ions (Fe2+) in mg/L and absorbance of the blank and standards in a table for graphing.
3. Construct a calibration graph from the above values and draw the best-fitting straight line through the data points. Determine the concentration of iron with its unit in the diluted unknown solution on the calibration graph.
4. From the diluted unknown concentration, calculate the concentration of iron in the original unknown solution.
5. Calculate the mass of iron in the solid unknown sample.
6. Calculate the percentage of iron in the unknown sample where:
% iron in unknown sample = (mass of iron in unknown sample / total mass of unknown sample) X 100%

CLEAN-UP

* Discard any of the remaining green solid into the blue waste baskets near the balances.
* Clean and rinse all glassware well with tap water, including the test tubes.
* Return the test tubes to the test tube racks.
* Return your glassware to the labelled locations. Make sure the rubber stoppers are placed on or nearby the volumetric flasks. The glassware does not need to be completely dry.

CALCULATIONS QUESTIONS
1. Use the given value for the concentration of iron in the stock solution and the volume you used to calculate the concentration of iron(II) ions (Fe2+) in mg/L in the blank and each of the three standard solutions.
2. Present the concentration of iron(II) ions (Fe2+) in mg/L and absorbance of the blank and standards in a table for graphing.
3. Construct a calibration graph from the above values and draw the best-fitting straight line through the data points. Determine the concentration of iron with its unit in the diluted unknown solution on the calibration graph.
4. From the diluted unknown concentration, calculate the concentration of iron in the original unknown solution.
5. Calculate the mass of iron in the solid unknown sample.
6. Calculate the percentage of iron in the unknown sample where:
% iron in unknown sample = (mass of iron in unknown sample / total mass of unknown sample) X 100%

Added by Uthman A.

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