penetapan kadar nikel dalam nikel sulfat (niso4)

8/17/2019 Penetapan Kadar Nikel Dalam Nikel Sulfat (NiSO4)

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PENETAPAN KADAR NIKEL

DALAM NIKEL SULFAT(NISO4)

Nama Kelompok :

Ahmad Pandu (4)

Nova Indah Nurmala (19)

Zsa Zsa Khafifah Octaviana (31)


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ENGLISH INDONESIAN


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DASAR

Garam nikel dapat diendapkan dengan pereaksi

organik dimetilglioksima (dalam alkohol) dalam

suasana basa lemah, membentuk endapan nikel

dimetilglioksima yang berwarna merah.

REAKSI

NiSO4 + 2C4H8N2O2+ 2NH4OH Ni(C4H7N2O2)2+ (NH4)2SO4+ 2H2O


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PERALATAN DAN BAHAN

Peralatan Bahan

Piala gelas 400 ml Sampel Nikel sulfat (NiSO4)

Kaca arlojiDimetilglioksima (C4H8N2O2) 1%

(dalam alkohol)

Tutup kaca Ammonium hidroksida (NH4OH)10%

Pengaduk Barium khlorida (BaCl2) 0,5N

Cawan kaca masir Asam khlorida (HCl) 4N

Vakum Air sulingDesikator Air suling panas

Kassa

Labu semprot

Kakitiga


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CARA KERJA

1. Timbang ± 0,1 gram NiSO4.7H2O.

2. Larutkan dengan ± 100 ml air suling dalam

piala 400 ml.

3. Panaskan larutan sampai ± 80°C(thermometer).

4. Bubuhi ± 15 ml C4H8N2O2 1 % (dalam alkohol).

5. Basakan dengan NH4OH 10 % sampai

terbentuk endapan dan tercium sedikit bauNH3


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6. Simpan piala dan isinya di atas penangas air

mendidih selama ½ - 1 jam

7. Uji pengendapan sempurna

8. Saring dengan cawan kaca masir G2/G3 atau

cawan Gooch

9. Cuci endapan dengan air panas sampai bebas

sulfat

10. Keringkan endapan dalam cawan kaca masir

pada oven dengan suhu 140 °C, didinginkan

dan ditimbang

11.

Lakukan sampai bobot tetap Ni(C4H7N2O2)2


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PENGHITUNGAN KADAR

Kadar Ni = x 100%

fk = Faktor kimia


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Karena merupakan senyawa non polar,

Dimetilglioksima tidak dapat melarut dalam

pelarut polar seperti air. Oleh karena itu, pelarut

untuk senyawa ini harus juga bersifat non polarseperti alkohol. Inilah alasan mengapa

Dimetilglioksima selalu dilarutkan dalam

alkohol.

Nikel Dimetilglioksima optimal pembentukannya dalamsuasana basa lemah (NH4OH), sedangkan Paladium

harus dalam keadaan asam (HCl). Selain

Dimetilglioksima, terdapat pula beberapa pereaksi

organik yang digunakan sebagai pengendap spesifik,

antara lain 8-Hidroksi Kuinolina dengan Alumuniumdan Magnesium, lalu Nitroso 2-Naftol dengan Kobalt.


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Endapan yang dihasilkan (Nikel Dimetilglioksima)

merupakan endapan merah dengan kerapatan yang

rendah dikarenakan volumenya yang besar. Hal ini

mengakibatkan endapannya mudah merayap

(creeping). Endapan tidak perlu dipijarkan, cukup

dengan pemanasan dengan oven bersuhu 1400C.

Oleh karena itu digunakan cawan kaca masir sebagai

penyaring. Endapan ini kecil kelarutannya dalam air

suling panas, oleh karena itu pencuci digunakan air

suling panas untuk mempermudah pencucian. Untuk

mempercepat pengeringan, pada tahap terakhirendapan dibilas dengan alkohol 1 : 1.


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PERTANYAAN & JAWABAN

1.Mengapa Dimetil Glioksima dilarutkan dalamalkohol?

Jawab : Karena merupakan senyawa non polar,

Dimetilglioksima tidak dapat melarut dalam

pelarut polar seperti air. Oleh karena itu, pelarut

untuk senyawa ini harus juga bersifat non polar

seperti alkohol.


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2. Mengapa larutan harus dipanaskan sampai

80°C?

Jawab : Karena suhu pemanasan mempengaruhilarutan. Pemanasan hinggga suhu 80 C

dilakukan agar terbentuk endapan yang

sempurna karena jika suhu kurang dari 80 C

endapan tidak akan mengendap sempurna danapabila suhu lebih dari 80 C pereaksi organik

akan rusak.


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3. Mengapa endapan harus dikeringkan pada suhu

140 °C?

Jawab : Karena 140 °C merupakan suhu yang

pas untuk mengeringkan endapan nikel.

Endapan nikel juga bersifat labil pada suhu di

atas 200 C.


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4. Mengapa endapan Ni+ terbentuk dalam basa

lemah?

Jawab : Karena jika diendapkan dalam suasana

netral tidak akan terbentuk endapan, dan jika

diendapkan dalam suasana basa kuat akan

terjadi kopresipitasi.


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5. Apakah Ni dapat diendapkan dengan pereaksi

non-organik?

Jawab : Tidak, karena dikhawatirkan apabila

diendapkan dengan garam (anorganik) dalam

suasana netral tidak akan terbentuk endapan

dan jika diendapkan dengan basa kuat

(anorganik) akan terjadi kopresipitasi.


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BASIC THEORY

Nickel salt can be precipitated with

Dimethylglyoxime, an organic reagent in a weak

base condition, forms nickel dimethylglyoxime

precipitate that is red colored.

CHEMICAL REACTION

NiSO4 + 2C4H8N2O2+ 2NH4OH Ni(C4H7N2O2)2+ (NH4)2SO4+ 2H2O


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REQUIRED TOOLS & MATERIALS

Tools Bahan

400 ml beaker glass Nickel sulfate (NiSO4) sample

Watch glassDimethylglyoxime (C4H8N2O2) 1% (in

alcohol solution)

Glass Ammonium hydroxide (NH

4OH) 10%

Stirrer Barium chloride (BaCl2) 0,5N

Sintered glass crucible Hydrochloric acid (HCl) 4N

Vacuum Distilled water

Desiccator Hot distilled water

Wire gauze

Wash bottle

Tripod

Test tubes


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PROCEDURES

1. Measure ± 0,1 gram of NiSO4.7H2O.2. Dilute with ± 100 ml distilled water in 400 ml

beaker glass.

3. Heat the solution until ± 80°C (using

thermometer).4. Add ± 15 ml C4H8N2O2 1 % (in alcohol

solution).

5. Add NH4OH 10 % until it forms precipitate

and smells of ammonia (NH3).6. Put the beaker along with the solution on

boiled-water bath for ½ - 1 hour.


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7. Do the test of perfect precipitation.

8. Filter the precipitate using a sintered glass

crucible (G2/G3).

9. Rinse the precipitate using hot distilled water

until the sulfate excess is cleared from the

precipitate.

10. Dry the precipitate in the oven in 140 °C.

11. Cool the precipitate inside the desiccator.

12. Do the 10th-11st steps until the precipitate’s(Ni(C4H7N2O2)2) constant weight is reached.


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RATE CALCULATION


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THEORY

Nickel salts can be precipitated with an organic

reagent, Dimethylglyoxime (C4H8N2O2,), resultingthe red-colored Nickel dimethylglyoxime

(Ni(C4H7N2O2)2) precipitate. Dimethylgyoxime is a

spesific non-polar organic reagent, and it is only

used to precipitate Nickel and Palladium.


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Because Dimethylglyoxime is a non-polar

compound, it cannot be dissolved in polar

solvents, like water. Thus, the suitable solvent for

this compound is, the solvent must also have anon-polar character, like alcohol. This is the

reason why Dimethylglyokximes are always

dissolved in alcohol.

Nickel Dimethylglyoximes are formed optimally in

weak base condition (using (NH4OH), while

Palladium precipitates should be formed in acid

condition (using HCl). Aside from Dimethylglyoxime,

there are other organic reagents that can be used toprecipitate Nickel salts or metals, e.g. 8-

Hydroxyquinoline with Alumunium and

Magnesium, and Nitroso 2-naphthol with Cobalt.


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The precipitate which is formed (Nickel

dimethylglyoxime) is a red-colored precipitate with a

low density. It’s low density is caused by it’s high

volume. This characteristic causes the precipitate to

creep in the filter. It is not required to burn the

precipitate, it is good enough to heat the precipitate in

the oven in 1400C.

That is why, it is advised to use a sintered glass

crucible as the filter. The precipitate has small

solubility in hot distilled water, thus hot distilled

water is used to rinse the precipitate and it eases therinsing. To hasten the drying time in the oven, at the

last step of rinsing the precipitate, the precipitate is

rinsed with 1:1 alcohol once.


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QUESTIONS &

ANSWERS

1. Why Dimethylglyoxime is dissolved in alcohol?

Answer : Because Dimethylglyoxime is a non-

polar compound, it cannot be dissolved in polar

solvents, like water. Thus, the suitable solvent forthis compound is, the solvent must also have a

non-polar character, like alcohol.


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2. Why is the solution heated until 80°C?

Answer : Because the temperature of the heating

affects the solution. Heating until 80°C is done so

the solution can form a perfect precipitate. If the

temperature is less than 80°C, the perfet

precipitate cannot be formed and if the

temperature is more than 80°C, the organic

reagent can be damaged.


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3. Why is the precipitate dried in 140 °C ?

Answer : Because 140 °C is the suitable

temperature to dry the nickel precipitate. The

nickel precipitate also exhibits volatility above

200 °C.


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4. Why is Ni+precipitate formed in weak base

Answer : Because if Ni+is precipitated in neutral

condition, no precipitate can be formed. And if

Ni+ is precipitated in strong base condition,

coprecipitation can occur.


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5. Can Ni+ be precipitated with inorganic reagents?

Answer : No, because it is concerned if Ni+ is

precipitated with salts (inorganic), no precipitate

will be formed, and if Ni+ is precipitated with

base (inorganic), coprecipitation will occur.


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6. What will happen if the solution is heated until

more than 80°C ?

Answer : If the solution is heated until more than

80°C , the organic reagent will be damaged.


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7. Why is hot distilled water used to rinse the

precipitate?

Answer : The precipitate has small solubility in

hot distilled water, thus hot distilled water is

used to rinse the precipitate and it eases therinsing.


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8. What are organic reagents?

Answer : Organic reagents are reagents which

are comprised of organic compounds.

An organic compound is any member of a large

class of gaseous, liquid or solid chemical

compounds whose molecules contain carbon. A

few types of carbon-containing compounds such

as carbides, carbonates, simple oxides of carbonand cyanides are considered inorganic.


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penetapan kadar nikel dalam nikel sulfat (niso4)

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