Qualitative Analysis of Group 1 Cations Flashcards
Used to detect the presence of specific ions in aqueous solutions
Qualitative Analysis
It answers the question, what is present in a sample?
Qualitative Analysis
The basis for qualitative
analysis is the fact that
the ions will undergo specific chemical reactions with certain reagents
to yield products that are observable.
The qualitative analysis of ions in a mixture follows ______
systematic method
Group I
(Ag+, Pb+, Hg2+)
The qualitative analysis of ions in a mixture follows systematic method that involves these steps:
- Addition of reagents that utilize the general properties of ions to separate major groups of ions.
- Separation of major groups to subgroups using reactions that will detect fewer general properties.
- Add reagents that will confirm the presence of individual ions.
These steps follow a scheme which separate cations into _____ according
to the solubilities of their compounds
five major groups
Group II
(Cu2+, Bi3+, Cd+, Hg2+, As3+, Sb3+, Sn4+)
cations produce very insoluble sulfides
so they can be precipitated by low amounts of sulfide ion; this can be achieved by
adding acidic solution of H2S.
Group II (Cu2+, Bi3, Cd, Hg2, As3, Sb3, Sn4)
Cations produce insoluble chlorides so they can be
precipitated using dilute HCI, while all other cation remains in solution.
Group I (Ag’, Pb, Hg2)
Group I (Ag’, Pb, Hg2) Cations produce insoluble chlorides so they can be
precipitated using ___ while all other cation ____
dilute HCl; remains in solution.
Group II (Cu2+, Bi3, Cd, Hg2, As3, Sb3, Sn4) cations produce very ___
so they can be precipitated by ____; this can be achieved by
adding acidic solution of __
insoluble sulfides; low amounts of sulfide ion; H2S
Cations produce insoluble chlorides
Group I (Ag’, Pb, Hg2)
If more precipitate is observed, then ______________
Centrifuge the mixture again.
General Techniques in Qualitative Analysis
- Complete Precipitation
- Remove supernatant liquid from precipitate
- Washing precipitate
- Heat solution below boiling point
- Evaporate Solution
- Test with pH and litmus paper
cations produce very insoluble sulfides
Group II (Cu2+, Bi3, Cd, Hg2, As3, Sb3, Sn4)
Add _______ of each of the following aqueous solutions to separate centrifuge tubes
0.1 M AgNO3, 0.2 M Pb(NO3)2 and 0.1 M Hg:(NO3)2. Then add 3 drops of 6 M HCl to each centrifuge tube. Record your observation.
20 drops
Add 20 drops of each of the following aqueous solutions to separate centrifuge tubes
___________. Then add 3 drops of 6 M HCl to
each centrifuge tube.
0.1 M AgNO3
0.2 M Pb(NO3)2
0.1 M Hg2(NO3)2
Add ___ drop of ___ to ensure that the ___ Is complete. If more
precipitate is observed, then centrifuge the mixture again.
Add one more drop of HCI to ensure that the precipitation Is complete.
___ the three mixtures to completely separate the solid precipitate from the
solution. Make sure that you ___ before you start.
Centrifuge; balance the centrifuge
What is done by placing a test tube containing water opposite to the test tube containing the precipitate in the centrifuge. The two test tubes should have approximately equal
weights.
Balancing
what may be discarded in the lab waste container.
supernatant solution
_______ the supernatant liquid into another ______ and save the precipitate for further study.
Decant; small test tube
Prepare a ___. Assemble a ___ and ___ to heat the water over the Bunsen burner until it is boiling.
water bath; tripod ; wire gauze
