Idea of the experiment:

(1) Qualitative investigation of [Zn2+] in a systemic

cycle.

(2) Preparation of different [Zn2+] compounds.

(3) Inter-conversion of [Zn2+] compounds.

Systemic Investigation of [Zn2+]

(SI - 13)

Systemic Investigation of [Zn2+]

(SI - 13)

White ppt. Zn3 (PO4)2

White gel. ppt. Zn (OH)2

Solution Na[ZnO2]

Exp. 1

Exp. 2

Exp. 3

HCl

Zn2+

(SI-13)Reagents Used:

- HCl (1:1 solution).- Sodium phosphate.- Sodium hydroxide.- Zinc chloride.

Add (1 ml) of sodium hydroxide solution to ca. (2 ml) of zinc chloride solution.What do you observe?

Exp. 1

Observation:

White gel. ppt. of Zn(OH)2. Equation:

2NaCl Zn(OH) 2NaOH ZnCl 22

Dissolve the precipitate obtained from experiment (1) in ca. (2 ml) NaOH solution.What do you observe?

Exp. 2

Observation:

The precipitate dissolves in NaOH.

Equation:

1. Add (1 ml) of HCl to the solution produced from exp. 2.

What do you observe?

Exp. 3

OH ZnONa NaOH Zn(OH) 222

Observation:White ppt. of Zn(OH)2.Equation:

222 ZnCl 2NaCl Zn(OH)2 4HCl ZnO2Na

FinallyDissolving the Zn3 (PO4)2 precipitate in

HCl, gives the starting solution of ZnCl2.

FinallyDissolving the Zn3 (PO4)2 precipitate in

HCl, gives the starting solution of ZnCl2.

1- Dissolve the precipitate obtained in (0.5 ml) of HCl and then add few drops of sodium phosphate.

What do you observe?

White ppt. of Zn3 (PO4)2.Observation:

Equation: 6NaCl PO Zn PO2Na 3ZnCl 243432

IF EXP. (IV) GIVES NO PRECIPITATE THEN CARRY

OUT EXP. V

IF EXP. (IV) GIVES NO PRECIPITATE THEN CARRY

OUT EXP. V

EXPERIMENT. VEXPERIMENT. V

To (2 ml) of the unknown solution add (1 ml) of NH4Cl, NH4OH until just alkaline, then add (2 ml) of (NH4)2CO3 solution.

Observation:

White ppt. This means that the solution may be contains (Ba2+, Sr2+ or Ca2+). Dissolve the white precipitate in hot acetic acid, then add (2 ml) of K2Cr2O7 solution:

If yellow ppt. If no ppt.

This means that (Ba2+) is

present.

Carry out (SI-14) to

confirm this result.

This means that (Sr2+) or (Ca2+) may be

Present.

Add (CaSO4) solution :

Observation:

If white ppt. If no ppt.This means that (Sr2+)

is present. Carry out

(SI-15) to confirm the

result

This means that (Ca2+)

is present. Carry out

(SI-16) to confirm the

result

Systemic Investigation of [Ba2+]

(SI - 14)Systemic Investigation of [Ba2+]

(SI - 14)

Idea of experiment:

(1) Qualitative investigation of [Ba2+] in a systemic

cycle.

(2) Preparation of different [Ba2+] compounds.

(3) Inter-conversion of [Ba2+] compounds.

Reagents Used:

- HNO3 (1:1 solution).- Sodium Sulphite- Amm. Oxalate- Sodium hydroxide.- Barium nitrate.

(SI - 14)

Exp.1Ba2+

Exp.2

Nitrate salt

White PPt. Barium sulphite

White ppt. Barium hydroxide

White ppt. Barium oxalate

Exp.3

HNO3

Exp. 1Add (1 ml) of amm. oxalate solution to ca. (2 ml) of barium nitrate solution.What do you observe?

Observation:White ppt. of barium oxalate.

Equation:

Exp. 2

Dissolve the precipitate from experiment (1) in (1 ml) dil. HNO3, then add (1 ml) of sodium sulphite solution.What do you observe?

3442

422423 NONH 2 OBaC OCNH )Ba(NO

Observation:White ppt. of barium sulphite.

Exp. 3Dissolve the precipitate from experiment (2) in (1 ml) dil. HNO3, then add (1 ml) of amm. hydroxide solution.What do you observe? Observation:

White ppt. of barium hydroxide.

Equation:

33323 NaNO 2 BaSO SONa )Ba(NO 2

Equation:

342

423 NONH 2 OH Ba OH2NH )Ba(NO

FinallyDissolve the precipitate formed from exp.3 in a few drops of HNO3. The product is the starting solution of barium nitrate.

FinallyDissolve the precipitate formed from exp.3 in a few drops of HNO3. The product is the starting solution of barium nitrate.

Idea of the experiment:

(1) Qualitative investigation of [Sr2+] in a systemic

cycle.

(2) Preparation of different [Sr2+] compounds.

(3) Inter-conversion of [Sr2+] compounds.

Systemic Investigation of [Sr2+]

(SI - 15)

Systemic Investigation of [Sr2+]

(SI - 15)

Reagents Used: - HNO3 (1:1 Solution).- Strontium nitrate.- Sodium Carbonate.- Ammonium oxalate.

Exp.1

Sr2+

White ppt.Sr C2 O4

Exp.2

HNO3

(SI - 15)

White ppt.Sr CO3

Nitrate salt

Exp. 1Add (1 ml) of sodium carbonate solution to ca (2 ml) of (Sr 2+)solution.What do you observe?

Observation:White ppt. of strontium carbonate.Equation:

Exp. 2Dissolve the precipitate from experiment (1) in (1 ml) dil. HNO3, then add (1 ml) of amm. oxalate solution.What do you observe?

Observation:White ppt. of strontium oxalate.

333223 NaNO 2 SrCO CONa )Sr(NO

FinallyDissolve the precipitate formed from exp.2

in a few drops of HNO3. The product is the

starting solution of strontium nitrate.

FinallyDissolve the precipitate formed from exp.2

in a few drops of HNO3. The product is the

starting solution of strontium nitrate.

Equation:

3442422423 NONH 2 OSrC OC)(NH )Sr(NO

Idea of the experiment:

(1) Qualitative investigation of [Ca2+] in a systemic

cycle.

(2) Preparation of different [Ca2+] compounds.

(3) Inter-conversion of [Ca2+] compounds.

Systemic Investigation of [Ca2+]

(SI - 12)

Systemic Investigation of [Ca2+]

(SI - 12)

Exp.1

Ca2+

White ppt.CaC2O4

Exp.2

HNO3

(SI - 16)

White ppt.CaCO3

Nitrate salt

Reagents Used:

- HNO3 (1:1 Solution).- Sodium Carbonate.- Ammonium Oxalate.

Add (1 ml) of sodium carbonate solution to ca (2 ml) of calcium nitrate solution.What do you observe?

Exp. 1

Observation:

White ppt. of calcium carbonate.

Equation:

Dissolve the precipitate from experiment (1) in (1ml) dil. HNO3, and then add (1 ml) of amm. Oxalate solution.What do you observe?

Exp. 2

2NaCl CaCO CONa CaCl 3322

Observation:

White ppt. of calcium oxalate.

FinallyDissolve the precipitate formed from exp.2 in a few drops of HNO3. The product is the starting solution of calcium nitrate.

FinallyDissolve the precipitate formed from exp.2 in a few drops of HNO3. The product is the starting solution of calcium nitrate.

Equation:

3442422423 NONH 2 OCaC OC)(NH )Ca(NO

IF EXP. (V) GIVES NO PRECIPITATE THEN CARRY

OUT EXP. VI

IF EXP. (V) GIVES NO PRECIPITATE THEN CARRY

OUT EXP. VI

EXPERIMENT. VIEXPERIMENT. VI

To (1 ml) of unknown solution add sodium hydroxide and then boil.

Observation:

If white ppt. If Ammonia odour evolved. If no observation.

This means that(Mg2+) is present.

Carry out (SI-17).toconfirms this result

This means that (NH4+) is

present.Carry outExp. VI-A

This means that(K+) or (Na+) may

be present.Carry out Exp. VI-B

Systemic Investigation of [Mg2+]

(SI - 17)Systemic Investigation of [Mg2+]

(SI - 17)

Idea of experiment:

(1) Qualitative investigation of [Mg2+] in a systemic

cycle.

(2) Preparation of different [Mg2+] compounds.

(3) Inter-conversion of [Mg2+] compounds.

Reagents Used:

- HCl (1:1 solution).

- Amm. Hydroxide.

- Magnesium Chloride

- Amm. Chloride.

- Sod. Phosphate.

White gel. ppt. Mg (OH)2

White ppt. Mg (NH4) PO4

Exp. 1

Exp. 2

HCl

Mg2+

(SI-13)

Exp. 1To (2 ml) of MgCl2 solution, add (1 ml) of NH4OH until just alkaline.What do you observe?

Observation:White gelatinous ppt. of. Magnesium hydroxide.Equation:

Exp. 2Dissolve the precipitate formed from exp.2 in a few drops of HCl, then add sodium phosphate solution in the presence of amm. chloride and ammonia solution.(cool the tube).What do you observe?

Cl2NH Mg(OH) OH2NH MgCl 4242

Observation:White crystalline precipitate from magnesium ammonium phosphate. (slow formation of ppt.).

Exp. 3Dissolve the precipitate from experiment (1) in (1 ml) dil. HCl, then add (1ml) of sodium hydroxide.What do you observe? Observation:

White ppt. of Mg (OH)2.

Equation:

Equation:

OH )POMg(NH NH OH HPO Mg 24432--

42

SONa Mg(OH) 2NaOH SOMg 422

4

FinallyDissolve the precipitate formed in exp.3 in dil HCl. The product is the starting solution of magnesium chloride.

FinallyDissolve the precipitate formed in exp.3 in dil HCl. The product is the starting solution of magnesium chloride.

Exp. VI-A

To (1 ml) of the unknown solution add (1 ml). of Nessler`s reagent. K2[HgI4].What do you observe? Observation:

Brown ppt., or brown or yellow coloration, is produced according to the amount of ammonia or of ammonium ions. (NH4)2 [HgI4].

Test for Ammonium radical:

Exp. VI-B

To (1 ml) of the unknown solution add (1 ml). of sodium cobaltinitrite solution.What do you observe? Observation:

Yellow precipitate of potassium-sodium cobalti-nitrite

Test for potassium radical:

Equation:

2NaCl )Co(NONaK

2KCl (excess) )Co(NONa 622623

3NaCl )Co(NOK

(excess) 3KCl )Co(NO Na 623623

If exp. VI-B gives no observation, then the solution contains Na+ radical.