29/09/06 Yuni Krisnandi 1

Kimia pada Kulit Bumi

Dr. Yuni K. Krisnandi

29/09/06 Yuni Krisnandi 2

Kulit Bumi(earth’s crust)

Kulit bumi (earth’s crust)

29/09/06 Yuni Krisnandi 3

The 10 Most Abundant Elements in the Earth's CrustSource: CRC Handbook of Chemistry and Physics, 77th Edition

Element Abundancepercent by weight

Abundanceparts per million by weight

Oxygen 46.1% 461,000

Silicon 28.2% 282,000

Aluminum 8.23% 82,300

Iron 5.63% 56,300

Calcium 4.15% 41,500

Sodium 2.36% 23,600

Magnesium 2.33% 23,300

Potassium 2.09% 20,900

Titanium 0.565% 5,650

Hydrogen 0.14% 1,400

29/09/06 Yuni Krisnandi 4

The 10 Most Abundant Compounds in the Earth's Crust

Source: Exploring Chemical Elements and their Compounds; David L. Heiserman, 1992

Compound Formula Abundancepercent by

weight

Abundanceparts per million by

weightSilicon dioxide SiO2 42.86% 428,600

Magnesium oxide MgO 35.07% 350,700

Ferrous oxide FeO 8.97% 89,700

Aluminum oxide Al2O3 6.99% 69,900

Calcium oxide CaO 4.37% 43,700

Sodium oxide Na2O 0.45% 4,500

Ferric oxide Fe2O3 0.36% 3,600

Titanium dioxide TiO2 0.33% 3,300

Chromic oxide Cr2O3 0.18% 1,800

Manganese dioxide MnO2 0.14% 1,400

29/09/06 Yuni Krisnandi 5

Unsur-unsur

Oksigen• Sumber:

– Oksida SiO2, Fe2O3, dll.

• Perolehan:– oksigen dapat diekstraksi dari udara yang dicairkan

melalui proses distilasi fraksionasi– Elektrolisis air– Pemanasan KClO3

29/09/06 Yuni Krisnandi 6

Silikon, Si

Si diproduksi dengan memanaskan pasir (SiO2) dengan karbon pada suhu mendekati 2200°C

SiO2 adalah senyawaan silikon yang paling umum, dan senyawa yang paling melimpah jumlahnya di kulit bumi.

Bentuk SiO2

- Pasir - Kwarsa- Opal- Agate- Silika gel koloid desiccant (menyerap air)

29/09/06 Yuni Krisnandi 7

Senyawaan dari Si• Silikon karbida (SiC)

keras mendekati intan amplas• Sodium silicate (Na2SiO3) air silika

pembuatan sabun, perekat dan pengawetan telur.

• Silikon tetraklorida (SiCl4) smoke screens• Silikon juga bahan yang penting untuk membuat

silicone, material yang digunakan sebagai pelumas, polishing agents, insulator listrik dan implan medik.

29/09/06 Yuni Krisnandi 8

Aluminium• Di alam, Al tidak pernah ditemukan dalam

keadaan bebas• Semua Al dari bumi selalu bergabung

dengan unsur2 lainnya • Dua senyawaan yg paling umum adalah

alum seperti kalium aluminum sulfat (KAl(SO4)2•12H2O), dan aluminum oksida (Al2O3).

29/09/06 Yuni Krisnandi 9

Perolehan AluminumDua proses yang ditemukan pada tahun 1880-an

meningkatkan perolehan Al dari alam:1. Proses Hall-Héroult (ditemukan oleh Charles Martin Hall,

an American chemist, dan Paul L. T. Héroult, a French chemist, yang menemukan secara terpisah pada tahun 1886) perolehan Al dari Aluminum oksida

2. Proses Bayer (ditemukan Karl Joseph Bayer, an Austrian chemist pada tahun 1888)Cara murah memperoleh Al2O3 dari bauksit Bauksit: bijih yang mengandung sejumlah besar aluminum hidroksida (Al2O3·3H2O)

Kedua proses ini masih digunakan sampai hari ini untuk menghasilkan hampir semua Al di dunia.

• 1852 $1200 per kilogram• 1859 $40 per kilogram• 1909 $0.60 per kilogram

29/09/06 Yuni Krisnandi 10

Proses Bayer • Extraction

– Gibbsite: Al(OH)3 + Na+ + OH-

---> Al(OH)4- + Na+

– Böhmite and Diaspore: AlO(OH) + Na+ + OH- + H2O

---> Al(OH)4- + Na+

• Precipitation– Al(OH)4- + Na+ ---> Al(OH)3 +

Na+ + OH-

• Calcination– 2Al(OH)3 ---> Al2O3 + 3H2O

29/09/06 Yuni Krisnandi 11

World Bauxite Mine Production, Reserves, and Reserve Base

(x1000 ton) Mine production Reserves Reserve base 2000 2001 Australia 200–,800 53,500 3,800,000 7,400,000Brazil 14,000 14,000 3,900,000 4,900,000PR China 9,000 9,200 720,000 2,000,000Guinea 15,000 15,000 7,400,000 8,600,000Guyana 2,400 2,000 700,000 900,000India 7,370 8,000 770,000 1,400,000Jamaica 11,100 13,000 2,000,000 2,500,000Russia 4,200 4,000 200,000 250,000Suriname 3,610 4,000 580,000 600,000United States NA NA 20,000 40,000Venezuela 4,200 4,400 320,000 350,000Other countries 10,800 10,200 4,100,000 4,700,000

29/09/06 Yuni Krisnandi 12

Kegunaan Aluminum

Al dan Al-alloy digunakan sebagai bahan baku untuk:

• Kaleng, foils, peralatan dapur, komponen pesawat terbang, roket, dll yg membutuhkan material yang kuat TAPI ringan

29/09/06 Yuni Krisnandi 13

Besi• Besi adalah logam yang termurah dan salah satu yang banyak

kelimpahannya di alam. • Baja adalah logam paduan yang komponen utamanya adalah besi dan

karbon dengan %(w/w) 0.02% and 1.7%• BEsi terutama diperoleh dari mineral: hematite (Fe2O3) and magnetite

(Fe3O4). The minerals taconite, limonite (FeO(OH)·nH2O) and siderite (FeCO3) are other important sources.

• Huge amounts of iron are used to make steel, an alloy of iron and carbon. Steel typically contains between 0.3% and 1.5% carbon, depending on the desired characteristics. The addition of other elements can give steel other useful properties. Small amounts of chromium improves durability and prevents rust (stainless steel); nickel increases durability and resistance to heat and acids; manganese increases strength and resistance to wear; molybdenum increases strength and resistance to heat; tungsten retains hardness at high temperatures; and vanadium increases strength and springiness.

• Steel is used to make paper clips, skyscrapers and everything in between.

29/09/06 Yuni Krisnandi 14

Kalsium• Although calcium is the fifth

most abundant element in the earth's crust, it is never found free in nature since it easily forms compounds by reacting with oxygen and water.

• Metallic calcium was first isolated by Sir Humphry Davy in 1808 through the electrolysis of a mixture of lime (CaO) and mercuric oxide (HgO). Today, metallic calcium is obtained by displacing calcium atoms in lime with atoms of aluminum in hot, low-pressure containers.

•

29/09/06 Yuni Krisnandi 15

Kegunaan Kalsium• Due to its high reactivity with common materials, there is very little demand for

metallic calcium. • It is used in some chemical processes to refine thorium, uranium and zirconium. • Calcium is also used to remove oxygen, sulfur and carbon from certain alloys. • Calcium can be alloyed with aluminum, beryllium, copper, lead and magnesium.

Calcium is also used in vacuum tubes as a getter, a material that combines with and removes trace gases from vacuum tubes.

• Calcium carbonate (CaCO3) is one of the common compounds of calcium. It is heated to form quicklime (CaO) which is then added to water (H2O). This forms another material known as slaked lime (Ca(OH)2) which is an inexpensive base material used throughout the chemical industry.

• Chalk, marble and limestone are all forms of calcium carbonate. • Calcium carbonate is used to make white paint, cleaning powder, toothpaste and

stomach antacids, among other things. • Other common compounds of calcium include: calcium sulfate (CaSO4), also known

as gypsum, which is used to make dry wall and plaster of Paris, • calcium nitrate (Ca(NO3)2), a naturally occurring fertilizer • calcium phosphate (Ca3(PO4)2), the main material found in bones and teeth.

29/09/06 Yuni Krisnandi 16

Referensi

• http://www.windows.ucar.edu/tour/link=/earth/geology/crust_elements.html

• http://en.wikipedia.org/wiki/Silicon• http://education.jlab.org/itselemental/ele01

3.html• http://environmentalchemistry.com/yogi/periodic/Fe.html• dst