1. SHREE MALLIKARJUN COLLEGE SYBSC
SAFETY: Refer to MSDS of nickel nitrate, nickel chloride, dimethylglyoxime, H2S gas, HCl, ethanol
-Dr. Mithil S. Fal Desai
Aim: To estimate the amount of nickel as Ni-DMG in the solution of nickel chloride-containing copper
chloride and free HCl.
Chemicals: Nickel salt (nickel nitrate, nickel chloride), dimethylglyoxime, H2S gas, HCl, ethanol.
Apparatus: Beaker, conical flask, funnel, Whatman 41, G4 crucible, glass rod with policemen, water bath,
oven.
Theory: Nickel(II) reacts with dimethylglyoxime [C4H6(NOH)2] to form a coordination complex, in which
Ni has four coordinationation number. The formation of the red chelate occurs quantitatively in an aqueous
solution at pH 5 to 9. The copper is first separated by selective precipitation, as copper interferes with the
quantitative precipitation of Ni. The Cu2+
is precipitate in the acidic solution as copper sulfide which can
be filtered off.
Reaction:
Cu2+
(aq) + H2S(g) CuS(s) ↓ + 2H+
(aq)
Ni2+
(aq) + 2C4H8N2O2(aq) [Ni(C4H7N2O2)2](s) ↓+ 2H+
(aq)
Procedure:
1. Pipette out 25mL of the solution in a 250 mL beaker and add 3 mL of concentrated HCl.
2. Pass H2S gas through the solution and allow the solution to settle. (Check for complete precipitation)
3. Filter and then boil the filtrate free from copper ions to expel the dissolved H2S gas. (Test with lead
acetate paper).
4. Cool the solution and add 25 mL of 1% dimethylgloxime solution to the beaker
5. Add 2 g NH4Cland 1:1 NH4OH (red color precipitate is formed) and keep the beaker on a water bath for
30 min.
6) After30 min, cool the solution and add 1-2 mL of DMGand 10 mL NH4OHalong the sides of the beaker
and check for complete precipitation.
7) Transfer the precipitate quantitatively in a previously weighed G4 crucible and wash the precipitate with
20 mL cold water.
8) Dry the G4 crucible in an oven for 45 min at 110 °C.
9) Cool and weigh the crucible containing the precipitate.
(To get constant weights, repeat the step 7 and 8)
10) The weight of precipitate quantitatively corresponds to the weight of [Ni(C4H7N2O2)2].
Observation
Table 1.
The constant
weight of G4
crucible without
precipitate
“W1’ (g)
The constant
weight of G4
crucible with
precipitate
“W2’ (g)
Weight of
[Ni(C4H7N2O2)2]
‘A’=W2 – W1 (g)
Molecular weight
of
[Ni(C4H7N2O2)2]
‘B’ (g)
Atomic weight of
Ni
‘C’(g)
Amount of ni in
25 mL
‘x' = A* C/B (g)
Result: Amount of nickel in 500 mL is ______g.
![SHREE MALLIKARJUN COLLEGE SYBSC
SAFETY: Refer to MSDS of nickel nitrate, nickel chloride, dimethylglyoxime, H2S gas, HCl, ethanol
-Dr. Mithil S. Fal Desai
Aim: To estimate the amount of nickel as Ni-DMG in the solution of nickel chloride-containing copper
chloride and free HCl.
Chemicals: Nickel salt (nickel nitrate, nickel chloride), dimethylglyoxime, H2S gas, HCl, ethanol.
Apparatus: Beaker, conical flask, funnel, Whatman 41, G4 crucible, glass rod with policemen, water bath,
oven.
Theory: Nickel(II) reacts with dimethylglyoxime [C4H6(NOH)2] to form a coordination complex, in which
Ni has four coordinationation number. The formation of the red chelate occurs quantitatively in an aqueous
solution at pH 5 to 9. The copper is first separated by selective precipitation, as copper interferes with the
quantitative precipitation of Ni. The Cu2+
is precipitate in the acidic solution as copper sulfide which can
be filtered off.
Reaction:
Cu2+
(aq) + H2S(g) CuS(s) ↓ + 2H+
(aq)
Ni2+
(aq) + 2C4H8N2O2(aq) [Ni(C4H7N2O2)2](s) ↓+ 2H+
(aq)
Procedure:
1. Pipette out 25mL of the solution in a 250 mL beaker and add 3 mL of concentrated HCl.
2. Pass H2S gas through the solution and allow the solution to settle. (Check for complete precipitation)
3. Filter and then boil the filtrate free from copper ions to expel the dissolved H2S gas. (Test with lead
acetate paper).
4. Cool the solution and add 25 mL of 1% dimethylgloxime solution to the beaker
5. Add 2 g NH4Cland 1:1 NH4OH (red color precipitate is formed) and keep the beaker on a water bath for
30 min.
6) After30 min, cool the solution and add 1-2 mL of DMGand 10 mL NH4OHalong the sides of the beaker
and check for complete precipitation.
7) Transfer the precipitate quantitatively in a previously weighed G4 crucible and wash the precipitate with
20 mL cold water.
8) Dry the G4 crucible in an oven for 45 min at 110 °C.
9) Cool and weigh the crucible containing the precipitate.
(To get constant weights, repeat the step 7 and 8)
10) The weight of precipitate quantitatively corresponds to the weight of [Ni(C4H7N2O2)2].
Observation
Table 1.
The constant
weight of G4
crucible without
precipitate
“W1’ (g)
The constant
weight of G4
crucible with
precipitate
“W2’ (g)
Weight of
[Ni(C4H7N2O2)2]
‘A’=W2 – W1 (g)
Molecular weight
of
[Ni(C4H7N2O2)2]
‘B’ (g)
Atomic weight of
Ni
‘C’(g)
Amount of ni in
25 mL
‘x' = A* C/B (g)
Result: Amount of nickel in 500 mL is ______g.](https://image.slidesharecdn.com/toestimatetheamountofnickelasni-dmginthesolutionofnickelchlorideinpresenceofcopper-201210164844/85/To-estimate-the-amount-of-nickel-as-ni-dmg-in-the-solution-of-nickel-chloride-in-presence-of-copper-1-320.jpg)
