Chem 112 Technical Abstract
Determination of Cations and Anions through Elimination and Confirmation Tests
By: Symantha Resendiz
Introduction
A topic of great importance to all scientists is the identification of compounds, which is relevant in all aspects of their work in some way shape or form. Weather it may be determining what is causing sickness or what is polluting the air, it is very prevalent in the science world. In project 2, identification of cations and anions was preformed through a series of confirmation and elimination tests that ultimately led to identifying an unknown ionic compound made of cations and anions.
Materials and Methods
Part 1- Cation Tests
To begin, 5 centrifuge tubes were added 10 drops of one cation and labeled correspondingly, and the initial color of each solution was recorded. To being the metal hydroxide test, each tube was then added 6 M NaOH drop wise (about 20 drops) until a precipitate was seen. To each solution that formed a precipitate, 10 more drops of 6 M NaOH were added. This was to test to see if any solution was amphoteric, where any insoluble metal precipitate dissolved after the additional 6 M NaOH was added. The results were recorded and each solution was disposed of. To being the ammonia test, 5 new centrifuge tubes were each added 10 drops of one cation and labeled correspondingly. 15 M NH4OH was then added drop wise (about 20 drops) to each solution and the color of the solution and/or the color of the precipitate formed was recorded. 10 more drops of 15 M NH4OH was added to each solution and any changes were recorded, and the solutions were disposed of. To begin the flame confirmation tests, 20 drops of each cation were added to its labeled centrifuge tube. A Bunsen burner was then connected to the gas jet and lit to where a sharp blue cone was visible in the flame. A Nichrome loop was then soaked in HCl and placed in the flame until there was no color change in the flame. This insured there was no further solution on the loop.
By: Symantha Resendiz
Introduction
A topic of great importance to all scientists is the identification of compounds, which is relevant in all aspects of their work in some way shape or form. Weather it may be determining what is causing sickness or what is polluting the air, it is very prevalent in the science world. In project 2, identification of cations and anions was preformed through a series of confirmation and elimination tests that ultimately led to identifying an unknown ionic compound made of cations and anions.
Materials and Methods
Part 1- Cation Tests
To begin, 5 centrifuge tubes were added 10 drops of one cation and labeled correspondingly, and the initial color of each solution was recorded. To being the metal hydroxide test, each tube was then added 6 M NaOH drop wise (about 20 drops) until a precipitate was seen. To each solution that formed a precipitate, 10 more drops of 6 M NaOH were added. This was to test to see if any solution was amphoteric, where any insoluble metal precipitate dissolved after the additional 6 M NaOH was added. The results were recorded and each solution was disposed of. To being the ammonia test, 5 new centrifuge tubes were each added 10 drops of one cation and labeled correspondingly. 15 M NH4OH was then added drop wise (about 20 drops) to each solution and the color of the solution and/or the color of the precipitate formed was recorded. 10 more drops of 15 M NH4OH was added to each solution and any changes were recorded, and the solutions were disposed of. To begin the flame confirmation tests, 20 drops of each cation were added to its labeled centrifuge tube. A Bunsen burner was then connected to the gas jet and lit to where a sharp blue cone was visible in the flame. A Nichrome loop was then soaked in HCl and placed in the flame until there was no color change in the flame. This insured there was no further solution on the loop.