Anion Analysis

1. Tests are made directly on different portions of the unknown solution, little to no individual separation

2. Elimination test - determines which ions are not present

What are the tactics for Anion Analysis

Perform Positive Test

What is done to the ions that are not eliminated in the Elimination test?

I-, Br-, Cl-

Which are the anions whose tests are done in order to prevent interference with other ions?

Volatile (6):
CO^{₃ 2-} , S^2-, SO3^2-, NO2^-, CN^-,OCl^-

Precipitate:

S2O3^2- (thiosulfate)

Give the Group A Anions:
Make Volatile or Precipitates with HCl.

ppt in CaCl₂ in HAc:

• C₂O₄^2-

• F-

• SiO3^2-(Silicon Trioxide)

ppt in BaCl_² in HAc:

• CrO4^2-

• SO4^2-

ppt in BaCl with NH4OH

• PO4^3-

• AsO4^3-

• AsO3^3-

• BO3^3-

Give the Group B Anions:

Form insoluble products with CaCl2 or BaCl2

PPT soluble in 0.25 NH4OH:

• Cl-

• Fe(CN)₆^3-

PPT is INSOLUBLE in 0.25 NH4OH

• Br-

• I-

• SCN-

• Fe(CN)64-

• CN-

Give the Group C Anions:

Insoluble Products in AgNO3 in HNO3

1. S^2-

2. SO3^2-

3. I^2-

4. S₂O^2-

5. NO₂^-

Give the Group D Anions:

Reduces Fe3+ to Fe2+ in acidic solution and when Fe(CN)_6³ is added, a dark blue ppt of

Fe Fe(CN)₆² is formed

Acronym: SSITN or Silly Snakes Invade the Night

Oxalate, Nitrate, Nitrite, Hypochlorite, Chlorate, Ferricyanide

Give the Group E Anions:

Oxidize pink MnCl2 to Brown MnCl3

ON NH CF

• ClO3-

• NO3-

• NO2-

• Ac-

• MnO4

Give the Group F Anions:

Soluble Group

1. HAc, NH4AC, Ca(NO3)2

2. CaC2O4, for oxalate

3. BaCl2

4. HCl

5. NH4OH

6. Salts of Phosphate, Arsenate, Arsenite

Elimination Test for : Chromate, Sulfate, Oxalate, Phosphate, Arsenate, Arsenite

- What do you add first to the sample?

- You get a WHITE PPT, what is the formula and ion?
-To the 1st centrifugate, what do you add?

-You get BaCrO4 / BaSO4, dissolve this with?
-TO the 2nd centrifugate, what do you add?
-What salts are the ppt?

1. HCl, BaCl2

2. Centrifugate & White ppt

3. SO4 ion

4. Peroxide and BaCl2

5. White PPT-BaSO4 confirms SO3+ & Centrifugate 2

6. NaAc

7. BaCrO4, confirms CrO4 ion

Positive Test for SO4 (Sulfate), SO3 (Sulfite), CrO4 (Chromate):

1.What is the first reagents added to the sample that separates SO3 and SO4?
2. What does this yield?

3.What does the white ppt confirm?

4.To 1st centrifugate, what do you add?

5.What does q4 yield?

6.To the centrifugate you add BaCl2 & ?

7.What does process 6 yield?

1. Magnesia and HNO3

2. If Yellow: Phosphate Ag3PO4 , if Red: Ag3AsO4 Arsenate

3. HCl and TA

4. Yellow PPT: As2S3

Positive Test for PO4 & AsO3

1. To the sample what are the first reagents added?

2. This yields a PPT and a centrifugate, what does the ppt confirm?

3. To the Centrifugate, what reagents are added?

4. What is the result of process 3?

1. TA (C2H4NS)

2. As2S4

3. HNO3 & Ammonium Molybdate

4. Yellow, Phosphate (Ammonium Phosphomolybdate)

Positive Test for PO4 if ARSENATE PRESENT

1. To the sample add Heat, HCl & ___ to remove Arsenate

2. What is the PPT yielded?

3. To the centrifugate, add?

4. What is the color of the ppt and what does it confirm?

1. HNO3, Fe(NO3)

2. ferrocyanide (prussian blue)

3. FeSCN , proves SCN

4. FeSO4

5. Turnball Blue (Ferricyanide)

Positive Test for SCN , Fe(CN)63-, Fe(CN)64-

1. What are the first 2 reagents added?

2. What does the first ppt prove?

3. What does the centrifugate contain?

4. What do you add to the red centrifugate?

5. What will this yield?

1.Hcl,H2o2

2.CO2

3.BaOH2

4.BaCO3

Positive Test for CO3 Ion

1. Add Zn,___, & ___

2. You will yield what gas?

3. Add Ba(__)2

4. Whites ppt:

1.NH4Ac

3.H2SO4

4.KMnO4 , colorless

Positive test for C2O4

1. Add HAc,___,Cd(NO3)2

2. You will yield CaC2O4

3. To CaC2O4, add?

4. This will yield ___ solution proving oxalate

1. 6M NaOH & Pb(NO3)

4. Black

Positive Test for S2-

1. Add ____ & ____ in a Vial

2. This will give you (Na2(Pb(OH)4) —Plumbite

3. Add Solution

4. This gives___ ppt of PbS

1. HNO3

2. AgNO3

4. Nh4OH

6. HNO3

7. White, AgCl

Positive Test for Cl-

1. Add__ until acidic

2. Boil to destroy H2S , add ___ once cooled

3. Decant

4. To the ppt of AgCl, add__

5. You will yield Ag(NH3)2 + HCL

6. Add ___

7. The ___ ppt of ___ will confirm Cl

1. HNO3

2. KMnO4

3. Yellow, Brown

Positive Test for Br-

1. To the solution from I-, add ___ & CCl4

2. Add ___ until there is presence of bromide

3. Result will show ____ or orange or Color in CCl4 layer

1.HNO3

2.CCl4

3.Fe(NO3)2

4. Purple

Positive Test for I-

1. Add ___

2. Cover Surface with ___

3. Add ___

4. Color __ in CCl4 Layer indicates I-

1.Hac

2.FeSO4

3.Brown

Positive Test for NO2

1. Dilute solution with H2O and add ___

2. Add___

3. Color___ solution proves NO2