The chemical reactions that are used in the anion spot tests in this experiment

Question

The chemical reactions that are used in the anion spot tests in this experiment are for the most part simple precipitation or acid-base reactions. Given the information in each test procedure, try to write the net ionic equation for the key reaction in each test.

A) CO3^2- Add 1ml of 6 HCl to 1 M Na2CO3

B) SO4^2- Add 1ml of 6 M HNO3 to 1 ml of 0.5 M Na2HPO4, then Add 1ml of 0.5 M (NH4)2MoO4

C) PO4^3- (Reactants are HPO4^2-, NH4^+, MoO4^2-, and H^+; products are (NH4)3PO4•12MoO3 and H2O; no oxidation or reduction occurs.) Add 1 ml 6 M HCl to 1 ml of 0.5 M Na2SO4. Add a few drops of 1 M BaCl2.

D) SO3^2- Add 1ml 6 M HCl to 1ml 0.5 M Na2SO3, then add BaSO4

E) SCN^- Add 1 ml 6 M acetic acid HC2H3O2 to 0.5 M KSCN then add 1-2 drops of 0.1 M Fe(NO3)3

F) Cl^- Add 1ml 6 M HNO3 to 1 ml 0.5 M NaCl. Add 2-3 drops of 0.1 M AgNO3

G) NO3^- (Take as reactants Al and NO3^-; as products NH3 and AlO2-; final equation also contains OH- and H2O as reactants). Add 1ml 6 M NaOH to 1 ml 0.5 M NaNO3, then add Al metal granules.

HELP PLEASE!!

Explanation / Answer

A) CO3^2- Add 1ml of 6 HCl to 1 M Na2CO3

The net ionic equation for the key reaction

2H+ (aq) + CO32- (aq) --------     H2O (l) +CO2 (g)

The Na and the Cl are irrelevant in this equation because they are simply spectator ions, therefore we only need to look at the H and the CO2 which produces water (a liquid and does not dissociate) and carbon dioxide (a gas which doesn't dissociate).

B) SO4^2-

Add 1 mL of 0.5 M Na2SO4 and 1 mL of 6 M HCl to a small test-tube. Next add a few drops of 1 M BaCl2. Ba2+ + 2Cl- + 2Na+ + SO42- => Ba2+ + SO42-+ 2Na+ + 2Cl-

Na+ and Cl- are spectator ions. BaSO4 is precipitate which is insoluble, so it stays together.

Ba2+ + SO42-   ---------à BaSO4

White precipitate of BaSO4 indicates the presence of the SO42- ion.

C) PO4^3-

Add 1 mL of 0.5 M Na2HPO4 and 1 mL of 6 M HNO3 to a small test tube. Next add a 1 mL of 0.5 M (NH4)2MoO4 and stir thoroughly. Place the test tube in the hot water bath and continue to stir. A yellow precipitate of indicates the presence of PO43-

Na2HPO4 + 12(NH4)2MoO4 + 23HNO3 = (NH4)3(PMo12O40) + 21NH4NO3 + 2NaNO3 + 12H2O

D) SO3^2-

Add 1ml 6 M HCl to 1ml 0.5 M Na2SO3, then add BaSO4

BaCl2 + Na2SO3 = 2NaCl + BaSO3

Ba2+ + SO32-------------à BaSO3

White precipitate of BaSO3 indicates the presence of the SO32- ion, which disappear on adding HCl.

E) SCN^- Add 1 ml 6 M acetic acid HC2H3O2 to 0.5 M KSCN then add 1-2 drops of 0.1 M Fe(NO3)3

A dark red solution indicates the presence of SCN-

Fe+3 (aq) + 3NO3-(aq) + 3 K+(aq) + 3 SCN-(aq)          --> Fe(SCN)+2(aq) + 2SCN-(aq) + 3K+(aq) + 3 NO3-(aq)

Cancelling out the spectator ions produces:

Fe+3(aq) + SCN-(aq) --> Fe(SCN)+2 (aq).

F) Cl^

- Add 1ml 6 M HNO3 to 1 ml 0.5 M NaCl. Add 2-3 drops of 0.1 M AgNO3

net ionic: Ag+(aq) + Cl¯(aq) ---> AgCl(s)

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