Methods Of Using Gravimetric Analysis Essay

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Theory
Gravimetric analysis is a technique that can determine the amount of an analyte through the measurement of mass. Essentially, in a pure compound, the mass of an ion can be determined. This can then be used to calculate the mass percent of this ion in an impure compound of a known quantity (Wired Chemist). This method of quantitative chemical analysis is demonstrated in the determination of the chloride content in an unknown compound.
The reaction equation of chloride ion precipitation by silver ion is as follows:
1)
This equation shows a precipitation reaction, in which a precipitate –an insoluble ionic solid – is formed as a result of cations and anions combining in an aqueous solution. Furthermore, in this lab, an unknown salt that is dissolved in water uses silver nitrate, a soluble silver salt, as a precipitating agent to precipitate silver chloride.
To determine if a precipitation reaction will occur, solubility rules are consulted. In this case, the silver cation is combined with the chloride anion (Schaffer and Herman, 2016). Knowing that the solubility product, or Ksp, of silver chloride is:
2)
it can be seen that the Ksp is small enough it can be considered negligible (Archer et al., 2016). (This expression for the Ksp of silver chloride is true when there is no excess silver, so the concentrations of both the silver cation and the chloride anion are equal to each other.) Because of this, the precipitation reaction can occur to form an insoluble
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