(I) Standardization of K₂Cr₂O₇

1. Rinse and fill the burette with K₂Cr₂O₇ solution.
2. Take 10 ml of standard FAS solution in a conical flask.
3. Add 5–10 ml of dilute H₂SO₄ solution in above flask.
4. Now add 2–3 drops of N-phenyl anthranilic acid indicator.
5. Titrate it against K₂Cr₂O₇ solution till the color changes from green to purple-red.
6. Note this reading from burette.
7. Repeat the same procedure and get the concordant readings.

(II) Titration of Sample FAS Solution with K₂Cr₂O₇

1. Rinse and fill the burette with K₂Cr₂O₇ solution.
2. Take 10 ml of sample FAS solution in a conical flask.
3. Add 5–10 ml of dilute H₂SO₄ solution in above flask.
4. Now add 2–3 drops of N-phenyl anthranilic acid indicator.
5. Titrate it against K₂Cr₂O₇ solution till the color changes from green to purple-red.
6. Repeat the same procedure and get the concordant readings.

Slide-1 Procedure

1. Add few drops of N-PAA (N-phenyle anthranilic acid) indicator in the conical flask
2. The colour of solution does not change.

Slide-1 Procedure

1. Set the normality of K2Cr2O7 and volume of FAS solution using slide bar, To start titration click on the start button.
2. Fix the nozzle opening size by nozzle open slider.Shake the flask while Titrating.
3. Titrate the solution till it turn to purple colour.

Safety Precautions

1. Wash the glassware properly with distilled water.
2. Rinse the burette and pipette with respective solutions.
3. Use dilute H₂SO₄ or dilute HCl to provide an acidic medium.
4. Always use freshly prepared indicator.
5. Read the upper meniscus in the burette (in case of colored solutions).

Discussion

This analysis is an important method to determine the amount of iron in any of its ores or alloys. The titration method is used widely to determine quantitative measurements of metals and their compounds in different industries. This method is simple, accurate, reproducible, and rapid.