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58 Cards in this Set
- Front
- Back
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What is the expected color of PbI_2?
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yellow
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What is the expected color of AgCrO_4?
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Red
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What is the expected color of Ag_2O?
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brown
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What is the color of Ag(S_2O_3)_2 ^3-?
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colorless
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What is the color of PbCrO_4?
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yellow
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What is the color of Hg_2Cl_2?
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white
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What is the color of PbCl_2?
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white
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What is the color of HgO? How is it formed?
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black
formed when Mercury I is mixed with OH- |
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Which three chlorides are insoluble?
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Ag, Hg_2, Pb
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What is unique about lead that allows it to be separated from Ag and mercury?
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It will dissolve when heated
(chromate will show the presence of the ion) |
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What solution will precipitate silver, mercury and lead ions?
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HCl
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When ammonia is added to the white precipitates from experiment one, if black precipitate is observed what ion is present?What would happen if silver was present?
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mercury
no color would be detected and you would need to centrifuge and add HNO_3 to test for silver |
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What is the color of Iron hydroxide? Fe(OH)_3
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red
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What is the color of Al(OH)_4-?
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colorless
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What is the color of the zinc sulfide ion ZnS?
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white
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What is the color of the zinc hydroxide ion Zn(OH)_2?
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white
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What is the color of Fe(SCN)^2+?
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red
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What is the color of zinc ammonia complex ion Zn(NH_3)_4^2+?
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colorless
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When excess ammonia is added to a solution containing either Zinc, iron, or aluminum a precipitate will form, How can you easily tell the difference between which ion is present?
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iron will form a red precipitate
zinc will form a white precipitate but then disappear as it forms the complex ion aluminum will form a white precipitate and the precipitate will remain |
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How can you separate zinc from iron and aluminum?
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add excess NH_3 and the zinc will dissolve and you can centrifuge and separate the zinc ion from the aluminum and iron precipitates
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When zinc forms its complex ion with ammonia what ion needs to be added to make zinc precipitate?
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sulfide
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How do you separate aluminum and iron once zinc has already been separated?
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add OH (hydroxide) because iron forms a precipitate with OH and aluminum forms a colorless solution. separate by centrifugation
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Once iron and aluminum have been centrifuged apart from each other how can you confirm the presence of each ion.
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To the colorless aluminum solution make a buffer with HCl and NH_3 if a precipitate forms then aluminum is present
To the red iron precipitate add HCl to dissolve it then add KSCN and if the solution turns red then iron is present |
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What color is BaCrO_4?
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yellow
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what color is Ca C_2O_4?
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white
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What is the color of the barium ion?
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colorless
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What is the color of Calcium hydroxide Ca(OH)_2?
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white
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What is the color of Calcium carbonate CaCO_3?
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white
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What is the color of BaC_2O_4?
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white
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What is the easy test that will help you detect the presence of the carbonate ion?
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add acid and it will give off bubbles
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When NaOH and NH_4+ are mixed what will be produced? How can you know for sure when the test is performed?
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NH_3 (gaseous) and water. You will smell the NH_3 gas if you cannot tell use pH paper
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How do you test for the presence of the potassium ion in a solution?
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concentrate the solution by heating it and then use the flame test and check for a purple flame through the blue glass
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In a solution containing either Ba, Ca, K, or NH_4 how can you separate them?
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K- flame test of supernatant from ammonium carbonate addition
NH_4- add OH Ba and Ca add carbonate |
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What is added to unknown solution to precipitate barium and calcium?
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ammonium carbonate so that it will precipitate and it will not interfere with the flame test
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Once barium and calcium have been separated from the other cations how do you separate them?
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make a buffer with acetic acid and ammonium acetate add chromate and if barium is present it will form a pale yellow precipitate. The supernatant is tested for sodium by adding potassium oxylate
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Which ion is filtered out when you view the flame through blue glass?
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sodium
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Why must the barium and calcium separation be performed in a buffered solution?
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chromate forms dichromate in acidic solution so if the solution is too acidic the test results will be skewed
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What is the color of silver sulfide?
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black
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What is the color of barium carbonate?
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white
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What is the color of silver phosphate?
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yellow
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What is the color of bromine water?
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dark yellow
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What is the color of barium sulfite?
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white
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What is the color of Fe(NO)^2+?
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brown
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When testing for anions how do you identify sulfide?
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add HNO_3 and AgNO_3. AgS will form as a black precipitate
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When testing for anions in an unknown solution and HNO_3 and AgNO_3 are added what does it mean if a black precipitate forms? What if the precipitate forms but is not black? What if there is no precipitate at all?
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black- sulfide confirmed
non-black precipitates- no sulfide, but one of the halides is present (Cl, Br, I) no precipitates- no S, Cl, Br, or I |
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WHat do you do to test for the Cl, I, and Br ions once they have been isolated?
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add HCl and Br_2 water. If no color forms then Br and I are absent. If the color does form then add hexane and mix observe the color to know if Br or I are present. If the hexane layer is purple iodide is present. If the hexane layer is yellow to brown the iodide is present
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Which four anions form a precipitate with barium ion?
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sulfate, sulfite, carbonate, phosphate
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Once sulfate, sulfite, carbonate, and phosphate have precipitated with barium and ammonia, which of these anions will not dissolve when HCl is added?
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sulfate
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If sulfate is present after the addition of the HCl and the carbonate test is finished, how should you test for the presence of the other two possible anions?
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1. test the supernatant with Br_2 water. If a white precipitate forms then sulfite is present.
2. test the supernatant with a molybdate solution. If a yellow precipitate forms then phosphate is present |
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Consider this statement and decide if it is true or false: A clear solution is always a colorless solution.
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false
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Pb(II), Ag(I), and Hg(I) ions all precipitate with the addition of which anion.
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Chloride
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A solution contains one of three possible cations: Pb, Ag, Hg. NaCl is added until precipitation is complete. The solution is then heated and the precipitate dissolves. The liquid is allowed to cool and a precipitate forms again. Which ion do I have in my unknown?
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lead
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Excess ammonia is added to isolate which cation from the other two
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Zinc
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A solution of Zinc is made slightly basic by adding a small amount of Ammonia, what would I expect to observe and what is the complex in solution?
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white precipitate of Zn(OH)_2
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Which cations are considered amphoteric?
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zinc and aluminum
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Why is it necessary to add acetate after dissolving the barium carbonate and calcium carbonate with acetic acid in step 1.
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prevents chromate from becoming dichromate
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You are given an unknown solution that contains one or more of the following unknowns: barium, calcium, potassium, and ammonium. Ammonium carbonate is added and no precipitation occurs. A purple flame is seen through the cobalt glass and the ammonium test turned the pH paper green. Which cations are present?
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potassium
ammonium |
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Match the following chemical used in one of the spot tests with the anion it is used to identify.
1. strong acid added to barium precipitate - watching for bubbles 2. silver ion 3. hexane layer 4. strong acid added to barium precipitate - watching for a precipitate that will not dissolve |
1.carbonate
2. sulfide (not sulfite) 3. Iodide or bromide 4. sulfate |
