An aqueous sample containing the following anions is analysed - HSC - SSCE Chemistry - Question 10 - 2011 - Paper 1
Question 10
An aqueous sample containing the following anions is analysed.
Cl⁻
CO₃²⁻
SO₄²⁻
In which order should the reagents be added to determine the amount of chlorid... show full transcript
Worked Solution & Example Answer:An aqueous sample containing the following anions is analysed - HSC - SSCE Chemistry - Question 10 - 2011 - Paper 1
Step 1
Reagent 1: HNO₃
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Answer
Add HNO₃ as the first reagent to remove any carbonate ions from the solution. HNO₃ will react with CO₃²⁻ to produce carbon dioxide and water, thus eliminating any interference from carbonate.
Step 2
Reagent 2: Ba(NO₃)₂
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Next, add Ba(NO₃)₂. This reagent reacts with sulfate ions (SO₄²⁻) to form barium sulfate (BaSO₄), which precipitates out of solution. This step helps to isolate the chloride ions by removing sulfate interference.
Step 3
Reagent 3: AgNO₃
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Finally, add AgNO₃. This reagent will precipitate the chloride ions by forming silver chloride (AgCl), allowing for the quantification of the chloride in the sample.
