HELP DUE TODAY Experiment observations: Experiment 1: We used unknown #2 Springs
ID: 1016398 • Letter: H
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HELP DUE TODAY
Experiment observations:
Experiment 1: We used unknown #2 Springs2016. This solution was a light green color that turned into a cloudy lighter green at the beginning. Then the cloudiness settled to the bottom. This happened after we added 8 drops of 6M HCl. We left the supernatant for step 5 and the precipitate for step 2.
Experiment 2: Using the precipitate from step 1. We put the test tube into a hot water bath where there still was a white precipitate. Meaning there is lead or silver present. The supernatant was saved for step 3 and the precipitate was saved for step 4.
Experiment 3: Using the supernatant from step 2. We added 0.5 M K2CrO4 solution. Precipitate did not form meaning there is no lead in the solution giving us silver instead.
Experiment 4: Using the precipitate from step 2. We added 6 M NH3 to the precipitate. The precipitate dissolved. We then added 15 drops of 6M HCl to the clear solution leaving a white precipitate. Our solution was acidic confirming there is silver in the unknown solution.
Experiment 5: Using the solution from step 1 we added 6 M NaOH which turned a green color when it was acidic and turned a blue color once it was basic. We then set the test tube into a hot water bath. The blue turned into a mossy green color then to a brownish black color. Meaning there is copper or iron is present. We saved the supernatant for steps 8, 9 and 10 and saved the precipitate for step 6.
Experiment 6: Using the precipitate from step 5 we added water then added 6 M H2SO4 until the solution turned acidic and dissolved. The solution also turned into a royal blue color. Then we added 6 M NH3 until the solution turned basic without a precipitate meaning there is copper in the solution.
Experiment 7: Was skipped because experiment 6 did not create a precipitate confirming there is no iron in the unknown solution.
Experiment 8: Using the solution from step 5 we made it slightly acidic by adding 6 M HCl. Creating a little bit of smoke. Then we added 6 M NH3 to make the solution basic which gave a yellow tint to the solution and a little cloudiness clear precipitate.
Experiment 9: Using the precipitate from step 8 we added hot water to was the precipitate. Then we added 6 M HNO3 until precipitate dissolves. Then added Aluminon reagent which turned the solution light orange. We also then added 6 M NH3 to turn the solution basic. Which turned the solution pinkish red. This confirms that we have Aluminum in the unknown solution.
Experiment 10: was skipped because experiment 9 confirmed we had Aluminum.
Unknowns found: Silver, Copper, and Aluminum
Cations present in unknown: AgCl, Cu^2+, and Al^3+
Net ionic equation for each experiment:
Silver:
Copper:
Aluminum:
Are the Cations correct?
What is the net ionic equations for each?
Explanation / Answer
Yes the ions are correct
a) Initially
Ag+ , Cu+ Al+3
Ag+ + 6MHCL --> AgCl (s)
Ag+ + Cl- --> AgCl (white precipitate)
b) Ag+ separated from the solution
Using the solution from step 1 we added 6 M NaOH which turned a green color when it was acidic and turned a blue color once it was basic. We then set the test tube into a hot water bath. The blue turned into a mossy green color then to a brownish black color:
[Cu(H2O)6]2+(aq) --> Cu(OH)2(s) [Blue colour]
Cu(OH)2--> CuO(s) (black)
CuO(s) (black)--> [Cu(H2O)6]2+(aq)
[Cu(H2O)6]2+(aq) + 4NH3(aq) --> [Cu(NH3)4]2+(aq)(blue)
c) Aluminon reagent which turned the solution light orange: this is confirmatory test for Al+3
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