Gravimetric Analysis of a Chloride Salt
Student:
Student No.
Lab Period:
Date Performed: October 22nd, 2015
Date Submitted: November 12th, 2015
Purpose:
Was to determine and illustrate gravimetric analysis involving different techniques to configure the amount of chloride in an unknown soluble salt sample.
Theory:
When solutions are mixed with a solvent, precipitates are often made within the process due to a precipitation reaction, caused by the mixture of two soluble compounds. Such process can be exploited in a common example through the combination of silver and chloride ions. The two ions create a solid form compound known as silver chloride. The equation of such formation is illustrated as such:
The precipitate formed is insoluble due to the completion of silver chloride; although the formation of this precipitate has slightly some solubility. This is expressed through the solubility product of Ksp :
When the soluble silver nitrate is added to the chloride solution, it will allow for a precipitate to be formed. This occurs until all the chloride ions are consumed leaving salt particles in the form of a solid.
The process of the precipitation reaction of silver chloride happens at a rapid state that can create unwanted ions to become present in the sample and precipitate to be formed. Such activities give a change in the data resulting in different mass levels resulting inaccuracies. Such reaction should be carried out in a slow matter to prevent the interference of ions with the precipitation reaction. The presence of nitric acid will prevent interactions of the unwanted ions.
Small particles known as colloids are a result of rapid precipitation of silver chloride; when particles are left in the state of a colloid, silver chloride particles are able to sift through the filter with ease and into the supernatant liquid. Coagulation of the silver chloride particles are then processed which can allow...