You will be given a small vial with an unknown substance. Your task is to use the following procedures to determine the ions
contained in the substance.
First you should observe all the visual aspects of your unknown. Note its color, crystal shape, odor, mixture of properties,
size of fragments, does it absorb water and any other feature you feel might be important. You should pulverize your unknown if it
contains large fragments. See instructor if you feel you must do this. Take approximately one half of your unknown and put it into a
gas collection bottle and put a rubber stopper on the bottle. Fill the bottle half full of distilled water. Your name should be on the
bottle along with your number. Your answer is reported by tube number not by your name.
You should be aware that no more unknown will be issued. You must conduct the analysis on the amount given. Use small
amounts to prevent running out. You must wear goggles at all times. Failure to do so will mean that you will be excluded from the
lab for one period. You should make sure that you keep accurate notes on all tests conducted. Each test should be checked at some
point. It is not advisable to repeat a test immediately as this results in carry over of improper procedures or substances.
When you are prepared to report an answer, you need to write your vial number and the ions that you wish to give as the
answer on the last page of this write-up. If all your answers are correct you will receive a grade of A. If your guess is incorrect you
may elect to make another attempt. This second attempt should be made after a thorough recheck of the analysis procedure. If the
second attempt is correct your grade will be a B. if the third attempt is not correct your grade will be based on how accurate your
answer was. Under no circumstances will a grade less than a C – be awarded for a completed analysis and correct worksheets. Your
success in this effort will be based on how well you are able to follow the procedures and how carefully you observe and report the
results. Some of the tests require the use of the Bunsen burner and some do not. It is important that you cooperate with your lab
partner(s) in the use of equipment. Individuals that do not do their own work will not be given credit for a completed analysis.
Chlorine /Bromide/Iodine Test: Cl- , Br-1, I -1
Add a small amount of silver nitrate to the unknown. If a white precipitate forms add a small amount of ammonium
hydroxide. The precipitate will dissolve at this point. Pour off the liquid and add some nitric acid to the liquid, and test the solution
with litmus paper to determine if the solution is acidic. If the unknown contains chlorine, a white chloride precipitate may form, if it
contains bromine, a creamy white precipitate forms, and if it contains Iodine, a yellow precipitate will form. It is possible that the
precipitate may be masked by some other ion precipitate. The use of a centrifuge after the addition of ammonia water can help to
separate contaminating ions.
Flame Test: Na+, K+, Ca2+, Sr2+, Cu2+, Ba2+, Li+
A flame test is used to test for a number of metallic ions. This test is based in the fact that each element has a unique
electron structure and produces a different color of light when heated in the flame of a Bunsen burner. First, saturate a Qtip with
distilled water. Then, dip it in the solid unknown and place it in the flame. The color produced should be noted and compared to the
given color chart.
Nitrate Test: Nitrate NO3-1
Add a small amount of ferrous sulfate to your unknown. While holding the test tube at an angle, slowly add a small amount
of 18M Sulfuric acid to the mixture. You must pour slowly so that the acid, which is more dense, will settle to the bottom without
much mixing. If the unknown contains nitrate you will see a thin brown ring form at the interface of the acid and the unknown. You
may need to wait a minute for the ring to form. Set the test tube in the rack so it remains undisturbed. Hold the tube against a white
paper background so as to make the brown ring more visible.
Borax Bead Test: Co +2, Mn +2
The Borax Bead test relies on the fact that small amounts of certain metals impart a characteristics color to glass. The glass
is produced from sodium tetraborate (borax) which is heated in the presence of the unknown. Heat a glass tube for a few moments
in a burner flame. Dip the tube into a small pile of borax and roll the tube around to coat it with borax. Return the tube to the flame
and heat until the borax melts and forms a layer of translucent glass on the end of the tube. While the borax glass is hot. Touch it to
a very small amount of solid unknown. Return the tube to the flame and melt the unknown into the borax glass. Rolling the tube
around will disperse the unknown into the glass. A deep blue color indicates cobalt. Red/brown indicates manganese. The bead will
turn very dark if too much unknown is used.
Sulfate Test: SO42Add a small amount of barium chloride to the unknown solution. A white precipitate that does not dissolve when
hydrochloric acid is added is evidence that the unknown contains sulfate.
Sulfite/ Carbonate Test: SO3-2, CO32Sulfur dioxide is produced when hydrochloric acid is added to and unknown containing sulfite. Sulfur dioxide removes the
color from potassium permanganate. Add a small amount of potassium permanganate to a test tube. Thoroughly clean a glass bend
with distilled water. Prepare a hot water bath. Add a small amount of unknown solid to the unknown liquid. Add to this unknown a
small amount of hydrochloric acid and immediately place the glass bend stopper in this tube. Put the other end of the glass tubing
into the potassium permanganate solution and immediately place the unknown in the hot water. Allow the unknown to heat a few
minutes. Check carefully to see if there is any change in the color of the potassium permanganate. Keeping aside a small sample of
the original of potassium permanganate is helpful. Do not remove the unknown from the hot water without first removing the
potassium permanganate because the reduced pressure of the cooling test tube will cause the permanganate to be forced into the
unknown.
The test for carbonate is conducted in the same way as the test for sulfite except that if the unknown contains carbonate
the gas produced is carbon dioxide, it is detected with limewater. Set up the same apparatus as for the sulfite test. Allow the
unknown to heat and watch for the appearance of a white cloudy substance in the limewater. It is very important that the test tube
that contains the limewater and the glass bend be washed thoroughly in distilled water to remove any possible traces of acid. Acid
will prevent the limewater from reacting properly.
Ammonium Test: NH4+1
A compound that contains ammonium reacts with sodium hydroxide to release ammonia gas. Ammonia gas dissolves in
water to produce a base. The presence of a base can be detected by using litmus paper (red turns blue). Prepare a hot water bath.
Dampen a piece of red litmus paper with distilled water. Add a small amount of sodium hydroxide to a solution containing the
unknown. Place the test tube into the hot water. Hold the litmus over the mouth of the tube. If the paper begins to turn blue from
the release of ammonia gas, ammonium ion is confirmed. Do not touch the tube with the paper as this will cause the paper to turn
blue due to the sodium hydroxide.
Iron Test: Fe+2, Fe+3
To test for the presence for ferrous (iron II) and ferric (iron III) ions you will use the solution containing your unknown. Add
a few drops of potassium ferrocyanid to your unknown. The appearance of a dark blue precipitate indicates the presence of ferric
ion (Fe+3). A few drops or potassium ferrocyanide will also produce a dark blue precipitate if ferrous ions (Fe+2) are present. Ferric
ions can also be detected by the addition of potassium thiocynate. Ferric ions will produce a dark red/brown solution upon the
addition of potassium thiocyanate.
Barium Test: Ba+2
The presence of the barium ion can be detected by using four separate reactions involving insoluble barium compounds.
You will use the solution of your unknown to conduct these tests. Add a small amount of potassium chromate to your unknown. The
formation of a yellow precipitate indicates that barium may be present. Add a small amount of the following solutions to separate
test tubes containing your unknown: ammonium carbonate, ammonium sulfate , and ammonium oxalate. The formation of a white
precipitate in each of these along with the formation of the previous yellow precipitate indicated the presence of barium ion.
Vial # _________
Guess # 1 __________
Name: ____________________________ Period: _____
Guess # 2 __________
Guess # 3 __________
Visual observation of my unknown: ______________________________________________________________________________
____________________________________________________________________________________________________________
Record all Notes, Observations, and Findings for each test below
Chloride /Bromide/Iodine Ion Test: ______________________________________________________________________________
_____________________________________________________________________________________________________
Iron/Cobalt/Copper Test: ______________________________________________________________________________________
_____________________________________________________________________________________________________
Sulfate Test: _________________________________________________________________________________________________
_____________________________________________________________________________________________________
Nitrate Test: _________________________________________________________________________________________________
_____________________________________________________________________________________________________
Borax Bead Test: _____________________________________________________________________________________________
_____________________________________________________________________________________________________
Sulfite/ Carbonate Test: ________________________________________________________________________________________
_____________________________________________________________________________________________________
Ammonium Test: _____________________________________________________________________________________________
_____________________________________________________________________________________________________
Barium Test: ________________________________________________________________________________________________
_____________________________________________________________________________________________________
Flame Test: _________________________________________________________________________________________________
_____________________________________________________________________________________________________
Tests we will not be performing:
Fluoride Test: F-1
Add a small amount of calcium nitrate to a solution containing the unknown. The formation of a very light amount of white
ppt. confirms the presence of fluoride.
Nickel Test: Ni+2
Add a few drops of the dimethylglyoxime to a small amount of unknown solution. The slow appearance of red “lake”
indicates the presence of nickel.
Cobalt Nitrate Test: Al+3, Zn +2
Cobalt Nitrate test is used for some metallic ions. Certain metal ions produce colored complexes when heated in the
presence of cobalt oxide. A piece of charcoal will be used to perform this procedure. Be aware that the charcoal gets hot and must
not be touched or placed in the trash can. All charcoals must be cooled with water and placed in the disposal container designated
by your instructor. Use a spatula to make a small cavity in the top of a piece of charcoal. Add a few drops of cobalt nitrate solution to
the cavity and use a blowpipe to direct the burner flame into the cavity. Add a small amount of solid unknown to the cavity. Put a
few drops of cobalt nitrate on the unknown and again direct the heat into the cavity with a blowpipe. Be careful not to burn your
hair while doing this. It is very important that the unknown be strongly heated. If the unknown contains Al +3, a blue residue will be
observed in or around the cavity. A green residue indicates Zn+2 .
Phosphate Test: PO43Add a small amount of nitric acid to a solution of the unknown. Add a small amount of ammonium molybdate to the
mixture containing the unknown and nitric acid. Heat the test tube in a hot water bath for a few minutes. The very slow formation of
a yellow ppt. indicates the presence of phosphate. This reaction may take 5 minutes to occur. Make sure that you give it plenty of
time.
Sulfide Test: S-2
An unknown containing sulfide will produce hydrogen sulfide gas if it is exposed to hydrochloric acid. Hydrogen sulfide gas
reacts with lead acetate to produce lead sulfide which is a dark colored substance. Prepare a strip of lead acetate paper by dipping a
piece of white paper into a solution of lead acetate. Add hydrochloric acid to a small amount of solution containing the unknown
and place the test tube into the water bath. Without allowing the lead acetate paper to touch the test tube, hold it near the mouth
of the test tube. If the paper darkens the presence of sulfide is confirmed.
Silver Test: Ag+1
This procedure can require some time so allow at least 20 minutes. Add a small amount of hydrochloric acid to a solution
containing your unknown. The formation of a white precipitate is evidence that this ion may be present. If a white precipitate forms
you will need to use about 10mL of your unknown solution. Add hydrochloric acid to the unknown until no more precipitate is
formed. This usually takes about 10 mL of acid. Filter resulting mixture and save the white residue. Next, add a few mL of
ammonium hydroxide to the residue in the filter paper. Collect the filtrate and add enough nitric acid to make the solution acid to
litmus (blue turns red). The formation of a white precipitate confirms the presence of silver. You must make sure that you have
added enough acid or the precipitate will not have a chance to form.
NaI
Cl/Br/I Test
Yellow
Fe/Co/Cu Test
No
Sulfate Test
No
Nitrate Test
No-thin Yellow ring
Borax Bead Test
White/Clear
NaBr
Light Yellow
No
No
No
White/Clear
Na2SO3
No
Yes-Dissolves w/HCl
No
Light Tan
NaCl
Yes & No Not really
cloudy settles quickly
White
No
No
No
White/Clear
Na2CO3
Light Tan -CO3
No
Yes-Dissolves w/HCl
No
White/Clear
CoSO4
No
Green
YES
No-thin Pink ring
Dark Blue
Co(NO3)2
No
Green
No
YES
Dark Blue
CoCl2
Green
No
No
Dark Blue
KBr
White Precipitate
Pink Solution
Light Yellow
No
No
No
White/Clear
KI
Yellow
No
No
No
White/Clear
K2CO3
Light Brown -CO3
No
Yes-Dissolves w/HCl
No
White/Clear
KCl
White
No
No
No
White/Clear
KNO3
No
No
No
Yes
White/Clear
LiCl
White
No
No
No
White/Clear
Li2SO4
No
No
YES
No
White/Clear
Li2CO3
Light Tan -CO3
White
No
No
CuCl
Black Precipitate
Dark Red /Rust
No
No
Coppery Red
CuSO4
No
Dark Red /Rust
YES
No
Hot Pink Coppery
Cu(NO3)2
No
Dark Red /Rust
No
Yes
Coppery Red
Ba(NO3)2
No
No
No
Yes
White/Clear
NH4Cl
White
No
No
No
White/Clear
(NH4)2SO4
No
No
YES
No
White/Clear
NH4I
Light Yellow
No
No
No
White/Clear
MnSO4
No
White
YES
No
Dark Red/Brown
MnCl2
White
Lilac
No
FeSO4
No
Light Blue
YES
No
Red Black
Fe(NO3)3
No
Dark Blue
No
YES
Black
FeCl3
White
Light Blue
No
No
Black
FeCl2
White
Dark Blue
No
No
Black
Sulfite Test
Carbonate Test
Ammonium Test
Barium Test
Flame Test
NaI
No
Clear
No
No
Orange
NaBr
No
Clear
No
No
Orange
Na2SO3
Brown then clear
Light Pink
No
No
Orange
NaCl
No
Clear
No
No
Orange
Na2CO3
No
Pink
No
No
Orange
CoSO4
No
Dissolves to Color
No Blue Precip. Pink Solution
Dark Cola Brown
Orange
Co(NO3)2
No
Dissolves to Color
No Green/Blue Precipitate
Dark Cola Brown
Orange
CoCl2
No
Dissolves to Color
Dark Cola Brown
Orange
KBr
No
Clear
No Green Precip. Pink
Solution
No
No
KI
No
Clear
No
No
K2CO3
No
Pink
No
No
KCl
No
Clear
No
No
KNO3
No
Clear
No
No
LiCl
No
Clear
No
No
Lilac/Light
Pink
Lilac/Light
Pink
Lilac/Light
Pink
Lilac/Light
Pink
Lilac/Light
Pink
Hot Pink
Li2SO4
No
Clear
No
No
Hot Pink
Li2CO3
No
Pink
No
Hot Pink
CuCl
No
Dissolves to Color
No Gold Precipitate
Greenish Yellow Precipitate
Blue-Green
CuSO4
No
Light Powder Blue
Rusty Orange Precipitate
Blue-Green
Cu(NO3)2
No
Dissolves to Color
No Light Blue + Black
Precipitate
No Black Precipitate
Redish Brown Muddy
Blue-Green
Ba(NO3)2
No
Clear
No
NH4Cl
No
Clear
YES
Light Yellow Cloudy
Precipitate
No
(NH4)2SO4
No
Clear
YES
No
NH4I
No
Clear
YES
No
MnSO4
No
Dissolves to Color
No Tan Precipitate
Dark Yellow w/ Black
Precip. Olive Oil Color
No
Light-Yellow
Yellow/Green
Orange w/
Lilac
Orange w/
Lilac
Orange w/
Lilac
No Change
Fe(NO3)3
No
Yellow
No Amber Solution
Orange Brown
FeSO4
No
Dissolves to Color
No Gree/Blue Precipitate
Mud Brown
FeCl3
No
Dissolves to Color
No Amber Solution
Orange Brown
FeCl2
No
Clear
No Black Precipitate
Mud Brown
MnCl2
Flashes
Pink/Orange
Flashes
Pink/Orange
Flashes
Pink/Orange
Flashes
Pink/Orange