Send the link below via email or IMCopy
Present to your audienceStart remote presentation
- Invited audience members will follow you as you navigate and present
- People invited to a presentation do not need a Prezi account
- This link expires 10 minutes after you close the presentation
- A maximum of 30 users can follow your presentation
- Learn more about this feature in our knowledge base article
Do you really want to delete this prezi?
Neither you, nor the coeditors you shared it with will be able to recover it again.
Make your likes visible on Facebook?
Connect your Facebook account to Prezi and let your likes appear on your timeline.
You can change this under Settings & Account at any time.
DETERMINATION OF SODIUM CHLORIDE (SALT) BY VOLHARD'S METHOD
Transcript of DETERMINATION OF SODIUM CHLORIDE (SALT) BY VOLHARD'S METHOD
Amount of NaCl in sample %
= (V2 – V1) x N x 5.844
W = Weight of sample
V2 = Titer volume of blank (mL)
V1 = Titer volume of sample (mL)
1mL of 0.1 N KSCN is equivalent to
5.844 mg of NaCl
Normality of KSCN = N1 x V1
N1 = Normality of AgNO3
V1 = Volume of AgNO3
V2 = Volume of KSCN
Nitric acid – To acidify the solution
AgNO3 – To precipitate chlorides
Chloroform – Covers the precipitate, separates it from water , makes it unable to dissolve
Ammonium ferric sulphate solution – As an indicator
Described by Jacob Volhard, a German chemist in 1874
Uses a back titration with potassium thiocyanate to determine the concentration of chloride ions in a solution
Useful where the titrations have to
be performed at low pH
Give advantage for halide analysis
Accurate and precise result
Easy detection of endpoint
Analyte is treated with the measured excess of Silver nitrate:
Cl- + Ag+ AgCl + Ag+ (excess)
The unreacted Silver ions are titrated with a standard solution of Thiocyanate ion,
using Fe (III) as indicator:
Ag+ + SCN- AgSCN
The first slight excess of Thiocyanate ion reacts with Fe3+ to form a dark red complex
Fe3+ + SCN-
Homogenise the sample
Weigh 2-10g of mix sample &
Shake for 30 seonds
Add 5mL of (1+1) nitric acid &
Dilute with D.I water to about 100mL
Add an excess amount of 0.1 N
Add 3mL of choloroform/nitrobenzene
Add 1 mL of ferric alum solution & Shake the content for 1 minute
Back titrate with 0.1N KSCN
(Amount of NaCl in spike sample - Amount of NaCl in sample) x 100
Amount of NaCl added
The volhard’s method is a better method for determining the salt content in a sample .
Although,it takes extra time , the results are accurate and precise .
It is applicable for all kind of sample which contains salt.
Common two methods:
Determination of Chloride ion concentration by Titration (Volhard's method)- University of Canterbury
AOAC Method 935.47
A Text Book of Quantitative Inorganic Analysis- Arthur I. Vogel