Answer to Question #267119 in General Chemistry for elen

Question

Case #2: Sodium chloride eye drops

Your pharmaceutical analysis company has been contacted by an important client and asked to analyze a batch of eye drops containing a NaCl solution. The description of your brief states that you are supposed to analyze the API in these tablets following standard quality assurance guidelines.

 

Typical analysis methods used for quality purposes are based on titration reactions. A certain volume of NaCl solution is titrated with silver nitrate (AgNO3). Potassium chromate is used as the appropriate indicator.

 

(a) Research the type of titration described.

Answer 1

Mohr's method, pioneered in 1855 by Karl Mohr, is one of the concentration-of-chloride determination methods used in precipitation titration. It is one of the applications of argentometric titration (meaning the silver(1) ion is used), which uses silver nitrate, AgNO₃, as a titrant.

• The Latin name for silver is argentum; it has the symbol Ag on the periodic table.

Potassium chromate, K₂CrO₄ is added to the titrant-analyte solution. The end point of the titration is signaled when a reddish-brown precipitate of silver chromate, Ag₂CrO₄, forms.