Hello, Please help me out! Thank you 1. Major precipitating anions from group IV

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1. Major precipitating anions from group IV cations are CrO42-, CO32-, and C204. chromates, carbonates, and oxalates are soluble in strong acids. 2. Chromate ion (CrO,2) is yellow, either in solution or in compounds. 3. Flame tests are useful in identifying several group IV and V cations. Ion Flame color Na yellow-orange Ion Ba2+ Ca2+ Sr2* Flame color green brick-red crimson violet Indicate a method or reagent that could be used to distinguish between the following pairs of solids. State the expected results clearly. 1. (24 pts) a. NH4CI and NaCI b. (NH)C0, and NIL,NO, c. BaCl2 and CaCl2 d. (NH)C,0, and Na,C0

Explanation / Answer

a) The salts contain the same anion, chloride (Cl-); the cations are different. Sodium ion (Na+) can be easily distinguished from ammonium ion (NH4+) by flame test. A solid salt of sodium gives a yellow-orange flame due to the formation of oxides. Ammonium ion doesn’t show any characteristic flame coloration.

b) The salts contain the same cation, ammonium (NH4+); the anions are different. Oxalate anion (C2O42-) can be distinguished from nitrate (NO3-) ion by adding a salt of a Group IV cation (calcium, Ca2+, for example). A solution of calcium chloride (CaCl2) produces a white precipitate of calcium oxalate (CaC2O4) when added to a solution of ammonium oxalate. Calcium chloride doesn’t give any precipitate with ammonium nitrate.

CaCl2 (aq) + (NH4)2C2O4 (aq) -----------> CaC2O4 (s) + 2 NH4Cl (aq)

c) BaCl2 and CaCl2 contain the same anion, chloride (Cl-), but the cations are different. Barium ion (Ba2+) and calcium ion (Ca2+) both react with a solution of ammonium sulfate [(NH4)2SO4] to give white precipitates of barium sulfate (BaSO4) and calcium sulfate (CaSO4).

BaCl2 (aq) + (NH4)2SO4 (aq) ---------> BaSO4 (s) + 2 NH4Cl (aq)

CaCl2 (aq) + (NH4)2SO4 (aq) ---------> CaSO4 (s) + 2 NH4Cl (aq)

CaSO4 is sparingly soluble in water while BaSO4 is completely insoluble. CaSO4 dissolves in dilute hydrochloric acid (HCl) to give soluble calcium chloride. BaSO4 is insoluble in acid and alkali.

CaSO4 (s) + 2 HCl (aq) --------> CaCl2 (aq) + H2SO4 (aq)

d) The situation is similar to the one described in part (a) above. The anions are the same while the cations are different. Sodium ion (Na+) can be easily distinguished from ammonium ion (NH4+) by flame test. A solid salt of sodium gives a yellow-orange flame due to the formation of oxides. Ammonium ion doesn’t show any characteristic flame coloration.

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