Lesson 3: Cation Analysis: Remaining Groups and Confirmatory Tests
This lesson continues the systematic separation and identification of the remaining cation groups.
- Group 4 Cations: The group reagent is gas in the presence of and . This precipitates cations like , , and as sulfides. Students will learn the confirmatory tests, such as the formation of a red complex with dimethylglyoxime (DMG) for .
- Group 5 Cations: The group reagent for Group 5 is ammonium carbonate () in the presence of and . Cations like , , and precipitate as carbonates. These can also be identified by their characteristic flame colors.
- Group 6 Cations: This group includes the cations that remain in the solution after all the other groups have been precipitated. It primarily consists of magnesium () and ammonium ion (). is tested with disodium hydrogen phosphate, and is tested by heating the salt with sodium hydroxide, which releases ammonia gas
