Photo AI
The flow diagram shows a series of tests that can be used to identify carbonate, chloride and sulfate ions present in a sample - HSC - SSCE Chemistry - Question 26 - 2006 - Paper 1
Question 26
The flow diagram shows a series of tests that can be used to identify carbonate, chloride and sulfate ions present in a sample. Step 1: Add excess HNO3(aq) Bubbles... show full transcript
Worked Solution & Example Answer:The flow diagram shows a series of tests that can be used to identify carbonate, chloride and sulfate ions present in a sample - HSC - SSCE Chemistry - Question 26 - 2006 - Paper 1
Step 1
Step 2
Explain why the analysis must be performed in the sequence given.
Answer
The analysis must be performed in the given sequence to ensure accurate identification of the ions present.
-
Step 1 with HNO3: Adding excess nitric acid first is crucial because it removes carbonate ions by releasing carbon dioxide gas, allowing for subsequent tests to focus on chloride and sulfate ions without interference.
-
Step 2 with Ba^2+: The addition of barium ions (Ba^2+) is next to identify sulfate ions by forming a white precipitate of barium sulfate (BaSO4). If sulfate ions are present, they will form this precipitate, which is essential for the analysis.
-
Step 3 with Ag+: Finally, filtering the mixture and adding silver ions (Ag^+) helps identify chloride ions by forming a white precipitate of silver chloride (AgCl). Without the sequential approach, the tests could yield overlapping results, making it difficult to conclusively identify each ion.