Answer to Question #227985 in General Chemistry for FiReClaN

Question

List and explain steps in carrying out a gravimetric analysis in
Precipitation
Digestion
Filtration
Washing
Drying
Weighing

Answer 1

The steps commonly followed in gravimetric analysis are

(1) preparation of a solution containing a known weight of the sample,

(2) separation of the desired constituent,

(3) weighing the isolated constituent,

(4) computation of the amount of the particular constituent in the sample from the observed weight of the isolated substance.

Digestion can help reduce the amount of coprecipitation. After the precipitate has formed and been allowed to "digest", the solution is carefully filtered. The filter is used to collect the precipitate; smaller particles are more difficult to filter.

Precipitates must be washed with liquid to remove all soluble impurities sticking with the precipitates. If precipitates get colloid during filtration the solution used for washing must contain electrolytes e. g. ammonium nitrate solution is used for washing iron (III) hydroxide.