The Gravimetric Analysis of Chloride Salt

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Gravimetric Analysis of a Chloride Salt

CHEM 1001

Purpose: To illustrate typical techniques used in gravimetric analysis by determining quantitatively the chloride content in an unknown soluble salt.

Theory: AgCl(s) is a very insoluble solid, yet still does have some solubility. Because of these traits, the following reaction is able to occur:
Ag+(aq) + Cl−(aq) → AgCl(s) .
This reaction is able to occur in both directions. When a soluble silver salt such as AgNO3 is added to a solution containing Cl−(aq) ion, then the added Ag+(aq) precipitates as AgCl(s) until all the chloride is consumed. For this particular reaction K sp = 1.6 x 10−10.

The reason why the solution is precipitated in an acidic medium become this causes the
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As the crucible is heated and the liquid inside the precipitate begin to evaporate the purple fades it it becomes a greyish-white colour.

True Percentage of Cl-= 56.52% ms1= 0.1222g
Volume of 0.1M AgNO3 = [(0.1222g x 0.55)/35.5g/mol]/0.1M + 5mL
Volume of 0.1M AgNO3 = 0.0189323L + 5mL
Volume of 0.1M AgNO3 = 18.9323mL + 5mL
Volume of 0.1M AgNO3 = 23.9323mL

ms2= 0.1492g
Volume of 0.1M AgNO3 = [(0.1492g x 0.55)/35.5g/mol]/0.1M + 5mL
Volume of 0.1M AgNO3 = 0.0231155L + 5mL
Volume of 0.1M AgNO3 = 23.1155mL + 5mL
Volume of 0.1M AgNO3 = 28.1155mL

mc1= 30.6795g mc2= 33.2337g

T= 105°C th= 30 minutes tc1= 5 minutes

mc1= 30.9907g mc2= 33.5634g

tc2= 5 minutes

mc1= 30.9218g mc2= 33.5664g

Mass of Cl- in precipitate (1)

mass in precipitate= (mass of crucible and sample) - (mass of crucible) mass in precipitate= 30.9218g - 30.6795g mass in precipitate= 0.2423g

Percent of Cl- in original sample (1)

moles of Cl- in sample= (mass of AgCl)/(MW of AgCl) moles of Cl- in sample= (0.2423g)/(143.321g/mol) moles of Cl- in sample= 0.001690611mol

mass of Cl- in sample= (0.001690611mol)(35.453g/mol) mass of Cl- in sample= 0.059937217g

% of Cl- in original sample= [(mass Cl-)/(mass of sample)] * 100
% of Cl- in original sample= (0.059937217g / 0.2423g) * 100
% of Cl- in original sample= 24.74%

Mass of Cl- in precipitate (2)

mass in precipitate= (mass of crucible and sample) - (mass of crucible) mass in
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