The table gives the results of chemical tests for some cations and anions - HSC - SSCE Chemistry - Question 15 - 2002 - Paper 1
Question 15
The table gives the results of chemical tests for some cations and anions. (ppt = precipitate)
| Ion | Add 0.1 M HCl | Add 0.1 M KSCN | Add 0.1 M Na2CO3 | Add 0.1... show full transcript
Worked Solution & Example Answer:The table gives the results of chemical tests for some cations and anions - HSC - SSCE Chemistry - Question 15 - 2002 - Paper 1
Step 1
Add cold 0.1 M HCl: no change
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Answer
The absence of a reaction suggests that there are no ions reacting with HCl, indicating that ions such as Ca2+, Ba2+, and Cl- may be present.
Step 2
Add cold 0.1 M KSCN: no change
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Answer
The lack of a red coloration indicates that Fe3+ is not present.
Step 3
Add 0.1 M Na2CO3: white ppt
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Answer
The formation of a white precipitate indicates the presence of either Ca2+ or Ba2+ ions.
Step 4
Add 0.1 M AgNO3: white ppt
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Answer
The white precipitate formed with AgNO3 suggests the presence of Cl- ions.
Step 5
Conclusion
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Answer
Based on the results, the unknown solution must contain ions inconsistent with Fe3+, supporting that it likely contains Ca2+ and other ions but not Fe3+. Thus, the most consistent conclusion is (A): The sample contained both CaCl2 and BaCl2.
