Transcript green chemistry-Part

Systemic Investigation of [Zn2+]
(SI - 13)
Idea of the experiment:
(1)Qualitativeinvestigation of [Zn2+] in a systemic
cycle.
(2) Preparation of different [Zn2+] compounds.
(3) Inter-conversion of [Zn2+] compounds.
Zn2+
Exp. 1
Exp. 2
HCl
White ppt.
Zn3 (PO4)2
Reagents Used:
- HCl (1:1 solution).
- Sodium phosphate.
- Sodium hydroxide.
- Zinc chloride.
White gel. ppt.
Zn (OH)2
Exp. 3
(SI-13)
Solution Na[ZnO2]
Exp. 1
Add (1 ml) of sodium hydroxide solution to ca. (2 ml)
of zinc chloride solution.
What do you observe?
Observation:
White gel. ppt. of Zn(OH)2.
Equation:
ZnCl2  2NaOH 
 Zn(OH)2   2NaCl
Exp. 2
Dissolve the precipitate obtained from experiment
(1) in ca. (2 ml) NaOH solution.
What do you observe?
Observation:
The precipitate dissolves in NaOH.
Equation:


Zn(OH)2  NaOH 
 Na ZnO2  H2O
Exp. 3
1. Add (1 ml) of HCl to the solution produced from
exp. 2.
What do you observe?
Observation:
White ppt. of Zn(OH)2.
Equation:


2Na ZnO2  4HCl 
 2 Zn(OH)2   2NaCl ZnCl2
1- Dissolve the precipitate obtained in (0.5 ml) of
HCl and then add few drops of sodium phosphate.
What do you observe?
Observation:
White ppt. of Zn3 (PO4)2.
Equation:
3ZnCl2  2Na3 PO4  Zn3 PO4 2   6NaCl
Finally
Dissolving the Zn3 (PO4)2 precipitate in
HCl, gives the starting solution of ZnCl2.
IF EXP. (IV) GIVES NO
PRECIPITATE THEN CARRY
OUT EXP. V
EXPERIMENT. 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 This means that (Sr2+) or (Ca2+) may be
present.
Present.
Carry out (SI-14) to
Add (CaSO4) solution :
confirm this result.
Observation:
If white ppt.
If no ppt.
This means that (Sr2+) This means that (Ca2+)
is present. Carry out
is present. Carry out
(SI-15) to confirm the (SI-16) to confirm the
result
result
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.
Ba2+
Exp.1
HNO3
White ppt.
Barium hydroxide
Exp.3
Nitrate
salt
White ppt.
Barium oxalate
Exp.2
White PPt.
Barium sulphite
(SI - 14)
Reagents Used:
- HNO3 (1:1 solution).
- Sodium Sulphite
- Amm. Oxalate
- Sodium hydroxide.
- Barium nitrate.
Exp. 1
Add (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:
Ba(NO3 )2  NH4 2 C2O4  BaC2O4   2 NH4 NO3
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?
Observation:
White ppt. of barium sulphite.
Equation:
Ba(NO3 ) 2  Na 2SO3 
 BaSO3   2 NaNO3
Exp. 3
Dissolve 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:
Ba(NO3 ) 2  2NH4OH Ba OH2   2 NH4 NO3
Finally
Dissolve the precipitate formed from exp.3
in a few drops of HNO3. The product is the
starting solution of barium nitrate.
Systemic Investigation of [Sr2+]
(SI - 15)
Idea of the experiment:
(1)Qualitativeinvestigation of [Sr2+] in a systemic
cycle.
(2) Preparation of different [Sr2+] compounds.
(3) Inter-conversion of [Sr2+] compounds.
Sr2+
HNO3
Nitrate salt
White ppt.
Exp.2
White ppt.
Sr CO3
Sr C2 O4
(SI - 15)
Reagents Used:
- HNO3 (1:1 Solution).
- Strontium nitrate.
- Sodium Carbonate.
- Ammonium oxalate.
Exp.1
Exp. 1
Add (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:
Sr(NO3 ) 2  Na2CO3  SrCO3   2 NaNO3
Exp. 2
Dissolve 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.
Equation:
Sr(NO3 ) 2  (NH4 ) 2 C2O4 
 SrC2O4   2 NH4 NO3
Finally
Dissolve the precipitate formed from exp.2
in a few drops of HNO3. The product is the
starting solution of strontium nitrate.
Systemic Investigation of [Ca2+]
(SI - 12)
Idea of the experiment:
(1)Qualitative investigationof [Ca2+] in a systemic
cycle.
(2) Preparation of different [Ca2+] compounds.
(3) Inter-conversion of [Ca2+] compounds.
Ca2+
HNO3
Nitrate salt
White ppt.
Exp.2
CaC2O4
- HNO3 (1:1 Solution).
- Sodium Carbonate.
- Ammonium Oxalate.
White ppt.
CaCO3
(SI - 16)
Reagents Used:
Exp.1
Exp. 1
Add (1 ml) of sodium carbonate solution to ca (2 ml)
of calcium nitrate solution.
What do you observe?
Observation:
White ppt. of calcium carbonate.
Equation:
CaCl2  Na 2CO3 CaCO3   2NaCl
Exp. 2
Dissolve the precipitate from experiment (1) in (1ml)
dil. HNO3, and then add (1 ml) of amm. Oxalate
solution.
What do you observe?
Observation:
White ppt. of calcium oxalate.
Equation:
Ca(NO3 ) 2  (NH4 ) 2 C2O4 
 CaC2O4   2 NH4 NO3
Finally
Dissolve the precipitate formed from exp.2
in a few drops of HNO3. The product is the
starting solution of calcium nitrate.
IF EXP. (V) GIVES NO
PRECIPITATE THEN CARRY
OUT EXP. VI
EXPERIMENT. 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).to
confirms this result
This means that (NH4+) is This means that
present.
(K+) or (Na+) may
Carry out
be present.
Exp. VI-A
Carry out
Exp. VI-B
Systemic Investigation of [Mg2+]
(SI - 17)
Idea of experiment:
(1)Qualitativeinvestigation of [Mg2+] in a systemic
cycle.
(2) Preparation of different [Mg2+] compounds.
(3) Inter-conversion of [Mg2+] compounds.
Mg2+
HCl
White ppt.
Mg (NH4) PO4
Exp. 1
Exp. 2
(SI-13)
Reagents Used:
- HCl (1:1 solution).
- Amm. Hydroxide.
- Magnesium Chloride
- Amm. Chloride.
- Sod. Phosphate.
White gel. ppt.
Mg (OH)2
Exp. 1
To (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:
MgCl2  2NH4OH  Mg(OH)2   2NH4Cl
Exp. 2
Dissolve 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?
Observation:
White crystalline precipitate from magnesium
ammonium phosphate. (slow formation of ppt.).
Equation:
Mg 2   HPO-4-  H2O  NH3 Mg(NH4 )PO4  H2O
Exp. 3
Dissolve 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:
MgSO4  2NaOH Mg(OH)2   Na2SO4
Finally
Dissolve the precipitate formed in exp.3 in
dil HCl. The product is the starting solution
of magnesium chloride.
Exp. VI-A
Test for Ammonium radical:
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].
Exp. VI-B
Test for potassium radical:
To (1 ml) of the unknown solution add (1 ml). of
sodium cobaltinitrite solution.
What do you observe?
Observation:
Yellow precipitate of potassium-sodium cobaltinitrite
Equation:
Na3 Co(NO2 )6  (excess) 2KCl  K 2 Na Co(NO2 )6   2NaCl
Na3 Co(NO2 )6   3KCl(excess)
 K3 Co(NO2 )6   3NaCl
If exp. VI-B gives no observation, then the solution
contains Na+ radical.