Preparation and Standardization of 0.1M Silver Nitrate

srikanth nagabiru December 02, 2012

1.0 OBJECTIVE

2.0 SCOPE

This SOP is applicable to Preparation and Standardization of 0.1M Silver Nitrate in company.

3.0 BACKGROUND

NIL

4.0 RESPONSIBILITY

4.1 QC-Chemist

4.2 Head-QC

5.0 PROCEDURE

5.1 Reagents : Silver nitrate, Sodium chloride, Eosin Y and water.

5.2 Glassware: Volumetric Flask, measuring cylinder, Burette, Conical Flask, beaker and Pipettes.

5.3 Principle:

The standardization involves direct titration of silver nitrate with sodium chloride results in the precipitation, forming a white curdy precipitate of AgCl and sodium nitrate.

The endpoint of the titration is a change of color from greenish-yellow to magenta which is given by the complex of the anion of the indicator, Eosin Y, with the excess silver ions. The titration is carried out in acidic conditions (about pH 2)and should be performed in the dark.

5.4 Preparation
Dissolve 17g of silver nitrate in sufficient chloride free water to produce 1000 ml.

5.5 Standardization

Note: The titration should be performed in the dark since solutions of silver are light sensitive and may decompose to elemental silver. The indicator, Eosin Y, also catalyzes the photodecomposition of the preparation. This is also the reason why the preparation needs to be standardized.

Weigh accurately about 0.1g sodium chloride, previously dried at about 110º C for 2 hours and dissolve in 5 ml of water. Add 5 ml of glacial acetic acid, 50 ml of methanol and 0.15 ml of eosin Y solution. Titrate with silver nitrate solution with constant stirring to purple end point.

Each ml of 0.1 M silver nitrate ≡ 0.005844 g of sodium chloride.

Perform a duplicate and calculate the Molarity factor (MF)
Note down the average value

5.3 Calculation

MF = W x actual molarity of silver Nitrate / V x 0.005844g (factor)

Where

V = Volume of silver nitrate consumed in ml.

W = Weight of sodium chloride. in g.

Example:

V=18.1 ml

W=0.10025gm

= 0.10025gmx0.1

18.1 x 0.005844 g