Argentometric Methods

Question 1

A classical analytical method which involves the use of AgNO3 as precipitating agent, are the most widely used methods for the determination of several anions.

Answer 1

Argentometric methods

Question 2

Titrations involving AgNO3 are based on the type of titrant used. True or false.

Answer 2

False. Indicator.

Question 3

The indirect determination of anion that uses ferric alum, FeNH4(SO4)2, as an indicator is called _____ discovered by _____ .

Answer 3

Volhard method, Jacob Volhard

Question 4

The direct determination of anion that uses K2CrO4, as an indicator is called _____ discovered by _____ .

Answer 4

Mohr method, Karl Friedrich Mohr

Question 5

The direct determination of anion that uses dichlorofluorescein (DCF), as an indicator is called _____ discovered by _____ .

Answer 5

Fajans method, Kazimierz Fajans

Question 6

Identify the argentometric method that uses the following indicators and titrant pairs.

Indicator, titrant
1. CrO4^2- (formed a precipitate with Ag+) , AgNO3
2. DCF (adsorbed on the AgCl precipitate) , AgNO3
3. Fe^3+ (formed a complex with SCN-) , KSCN

Answer 6

1. Mohr
2. Fajans
3. Volhard

Question 7

Determine if Volhard, Mohr, Fajan
1. Indirect determination of anion
2. Direct determination of anion
3. In slightly basic medium
4. In acidic medium
5. Endpoint: green or pink mixture
6. Endpoint: blood-red complex
7. Endpoint: red precipitates
8. Indicator: Fe3+
9. Indicator: DCF
10. Indicator: CrO4
11. Titrant: AgNO3
12. Titrant: KSCN

Answer 7

1. Volhard
2. Mohr, Fajans
3. Mohr
4. Volhard
5. Fajans (G: free form, P: adsorbed)
6. Volhard
7. Mohr
8. Volhard
9. Fajans
10. Mohr
11. Mohr, Fajans
12. Volhard

Question 8

In Fajans method, specifically for other anions such as Br-, I-, and SCN-, the more suitable adsorption indicator called ______is used to give sharper end points during titrations

Answer 8

Tetrabromofluorescein (or eosin)