The Identification of an Unknown Substance Using a Series of Tests
Project 2
Chemistry 111 – 552
Peyton Farmer*, Primary Author
Partners: Jacob Hicks and Abigail Boudreau
TA: Ming Uei Hung
Introduction
The purpose of this experiment was to use elimination and confirmation tests for both cations and anions, which then allowed the unknown substance to be identified by using logic trees of known solutions. Some qualitative characteristics of chemicals such as the formation of a precipitate, the color of the solution, and the color of the flame when the chemical was heated were used to create a logic tree, which allowed for the unknown compound to be identified with simple yes/no questions.
Materials and Methods
Part One:
In the metal hydroxide test, the first step was to add 10 drops of …show more content…
Sodium hydroxide was mixed with all cations, zinc, copper (II), cobalt (II), and potassium. Potassium, because it is a Group I metal, was not able to react with the sodium hydroxide to form a precipitate. The other three cations, copper (II), cobalt (II) and zinc, formed a precipitate with the initial reaction. When excess base (NaOH) was added to the solution, the white precipitate zinc initially formed was dissolved, therefore zinc was identified as an amphoteric metal hydroxide. Next, the ammonium hydroxide test was performed to identify the amine complexes and insoluble hydroxides of copper(II), cobalt (II) and zinc. Once again, potassium did not form a precipitate or amine complex. According to the lab manual, when transition metals mix with enough ammonia, they form colored complexes. Copper(II), cobalt (II), and zinc all formed metal hydroxides with the initial reaction of ammonium hydroxide. When excess ammonium hydroxide was added, they all dissolved the metal hydroxides and formed amine
Project 2
Chemistry 111 – 552
Peyton Farmer*, Primary Author
Partners: Jacob Hicks and Abigail Boudreau
TA: Ming Uei Hung
Introduction
The purpose of this experiment was to use elimination and confirmation tests for both cations and anions, which then allowed the unknown substance to be identified by using logic trees of known solutions. Some qualitative characteristics of chemicals such as the formation of a precipitate, the color of the solution, and the color of the flame when the chemical was heated were used to create a logic tree, which allowed for the unknown compound to be identified with simple yes/no questions.
Materials and Methods
Part One:
In the metal hydroxide test, the first step was to add 10 drops of …show more content…
Sodium hydroxide was mixed with all cations, zinc, copper (II), cobalt (II), and potassium. Potassium, because it is a Group I metal, was not able to react with the sodium hydroxide to form a precipitate. The other three cations, copper (II), cobalt (II) and zinc, formed a precipitate with the initial reaction. When excess base (NaOH) was added to the solution, the white precipitate zinc initially formed was dissolved, therefore zinc was identified as an amphoteric metal hydroxide. Next, the ammonium hydroxide test was performed to identify the amine complexes and insoluble hydroxides of copper(II), cobalt (II) and zinc. Once again, potassium did not form a precipitate or amine complex. According to the lab manual, when transition metals mix with enough ammonia, they form colored complexes. Copper(II), cobalt (II), and zinc all formed metal hydroxides with the initial reaction of ammonium hydroxide. When excess ammonium hydroxide was added, they all dissolved the metal hydroxides and formed amine