1) The document describes the Mohr's method for determining the concentration of silver nitrate (AgNO3) solution by titrating it against a standard sodium chloride (NaCl) solution. 2) In the titration, silver ions from AgNO3 react quantitatively with chloride ions from NaCl to form a precipitate of silver chloride. The endpoint is reached when excess Ag+ ions react with chromate ions from a potassium chromate indicator to form a red-brown precipitate of silver chromate. 3) The procedure involves titrating a known concentration of NaCl solution against the AgNO3 solution to determine its molarity, using potassium chromate as the indicator.

1. SHREE MALLIKARJUN COLLEGE CLASS:TYBSC
SAFETY: Refer to MSDS of sodium chloride, potassiumchromate and silver nitrate. -Dr. Mithil S. Fal Desai
Aim: Determine the strength in grams per litre of a given AgNO3 solution being provided
N/30 NaCl solution by Mohr’s method.
Chemicals: Sodium chloride, potassium chromate and silver nitrate.
Apparatus: Standard volumetric flask, pipette, burette, conical flask, beakers, funnel and glass
rod.
Theory: Mohr’s method is used to determine the chloride ion concentration by titrating with silver
nitrate. Using pure sodium chloride the strength of silver ions can be also determined as the Ag(I)
ions react with chloride ions, quantitatively, to form a precipitate of silver chloride.
Ag+
(aq) + Cl-
(aq)  AgCl(s)
At the endpoint, all the chloride ions are precipitated and excess Ag(I) ions react with the chromate
ions, to form a red-brown precipitate of silver chromate.
2Ag+
(aq) + CrO4
2-
(aq) → Ag2CrO4(s)
The pH of the sample solutions should be 6-10. If the solutions are acidic, the gravimetric method
or Volhard’s method is more suitable.
Procedure:
A) Preparation of 0.033 N (N/30) NaCl. calculate
B) Preparation of indicator: dissolve 2 g of KCrO4 in 40 mL of distilled water.
C) Estimation of the strength of the given AgNO3 solution.
Rinse and fill the burette with given AgNO3 solution. Pipette out N/30 mL of NaCl solution in a
conical flask. Add 20 mL of distilled water and 1 mL potassium chromate indicator. Titrate the
solution in the flask against AgNO3 until the red-brown colour of silver chromate is observed.
Repeat the titration to get constant readings.
Results: i) Strength of AgNO3 solution is =____N
=____gL-1
Further reading (available in the library)
2) Vogel’s textbook of quantitative chemical analysis, J. Mendham, R. C. Denney, J. D. Barns, M.
Thomas, B. Sivasankar, Pearson India Education, 6th Edition.
Question
1) What is Volhard’s method?
2) Can we use KMnO4 as an indicator in this titration?
3) What is the advantage of Volhard’s method over Mohr’s method?