April 2011 - Jejaring Kimia

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April 19, 2011

DAMPAK PERUBAHAN IKLIM TERHADAP MANUSIA

April 19, 2011
Berikut adalah fakta-fakta yang telah ditimbulkan akibat dari perubahan iklim. Fakta ini diambil dari Climate Change Kit yang merupakan bagian dari Pidato Maha Guru Ching Hai pada saat Konferensi Perubahaan Iklim COP16 di Cancun Meksiko, 18 Dasember 2010. Untuk informasi lebih lengkap Anda dapat mengunjungi situs SupremeMaster TV atau mendownload langsung melalui situs yang sama. Perubahan iklim dan pemanasan global adalah suatu fenomena yang mau tidak mau harus kita hadapi. Tapi belum terlambat untuk menyelamatkan bumi kita. Lakukan hal sederhana mulai dari hemat energi dan minimalisasi pemakaian kendaraan serta menjaga lingkungan dari sampah; minimalisasi konsumsi daging juga merupakan saran yang baik walaupun sulit untuk dilakukan, dekatkan diri Anda dengan tahu dan tempe, karena dua makanan ini bisa membantu mengurangi emisi karbon yang jumlah sudah melebihi ambang batas. Dunia menghasilkan emisi CO2 lebih dari 30 milyar ton tiap tahunnya, ini belum termasuk emisi non CO2 seperti gas metana, SO2, NO, termasuk juga freon.

Simak fakta-fakta berikut ini, mudah-mudahan menggerakkan hati kita melakukan hal kecil yang bisa menyelematkan dunia.

1. PENGUNGSI IKLIM

  • Terdapat sekitar 25-30 juta pengungsi iklim. Jumlah ini dapat meningkat sampai 200 juta, atau sampai 1 miliar pada tahun 2050
  • “Desa pengungsi iklim” Nepal pertama yang berisi 150 orang terpaksa dipindahkan karena kekurangan air akibat perubahan iklim. (Juli 2010)

2. KONFLIK

  • Komunitas Intelijen Amerika Serikat menganggap pemanasan global sebagai ancaman keamanan yang serius. Analis intelijen terkenal AS Thomas Fingar menyatakan bahwa banjir dan kekeringan akan segera menyebabkan migrasi masal dan kegelisahan di banyak bagian di dunia. (2010)
  • Bukti merujuk pada pemanasan global sebagai penyebab utama dari kekerasan di Darfur.

3. PENYAKIT

  • Temperatur yang memanas menyebabkan penyebaran malaria, virus Bluetongue, virus West Nile, demam berdarah, dan penyakit-penyakit lainnya yang mencapai jutaan orang lebih banyak dan mereka yang belum pernah terkena sebelumnya, pada lintang yang lebih tinggi atau pada benua-benua baru.
  • Sebanyak 400 juta orang lagi dapat terkena malaria pada tahun 2080 karena perubahan iklim
  • Lebih banyak penyakit pernapasan seperti asma dan penyakit mental yang berhubungan dengan bencana diperkirakan terjadi dengan pemanasan global

4. KEMATIAN

Bencana-bencana perubahan iklim sudah bertanggung jawab untuk sekitar 315.000 kematian setiap tahun, dengan 325 juta orang lain yang terkena dampaknya secara serius.

5. KEKURANGAN MAKANAN

  • Setengah dari populasi dunia akan menghadapi kekurangan makanan yang serius dalam abad ini.
  • Panen sudah dipersulit oleh kekeringan atau banjir di Rusia, Jerman, Kanada, Argentina, Australia, Ukraina, Pakistan, dan lain-lain. (Sept 2010)
  • Harga makanan naik 5% secara global pada bulan Agustus 2010. Di Mozambik, reaksi kerusuhan karena kenaikan harga roti menyebabkan 10 kematian dan 300 luka-luka. (Sept 2010)
  • Harga makanan tinggi yang memicu kerusuhan mematikan di seluruh dunia pada tahun 2008 adalah akibat kombinasi dari perubahan iklim dan meningkatnya permintaan untuk makanan ternak dari populasi di India dan China.
  • Jumlah orang yang masih menderita kelaparan melebihi 1 miliar untuk pertama kalinya pada tahun 2009
  • Lebih dari 9 juta orang meninggal di seluruh dunia setiap tahunnya karena kelaparan dan kekurangan makanan. Lima juta adalah anak-anak.

6. KEKURANGAN AIR

  • Sungai-sungai dunia sedang berada dalam “kondisi krisis” pada skala global. Persediaan air untuk hampir 80% dari populasi dunia sedang sangat terancam. Hampir sepertiga dari sumber air yang dikaji diketahui juga terancam akibat kehilangan keanekaragaman hayati
  • Laporan daerah yang baru-baru ini mengalami kekurangan air: Persediaan air Timur Tengah sudah menyusut sampai seperempat dari tingkatnya pada tahun 1960; Sungai Tigris dan Efrat menyusut sampai kurang dari sepertiga dari tingkat normalnya karena kekeringan; Kerajaan Inggris semakin panas, musim panas yang lebih kering dapat menyebabkan kekurangan air yang ekstrim karena aliran sungai berkurang 80%.
  • Sumber-sumber dari air tanah untuk sumur, yang mendukung setengah dari populasi dunia kita, semakin mengering.
  • 1,1 miliar orang kekurangan akses untuk air minum yang aman. (2005)
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Rino Safrizal
Jejaring Kimia Updated at: April 19, 2011

April 17, 2011

POLA MAKAN DAGING DIBANDINGKAN DENGAN POLA MAKAN VEGAN

April 17, 2011

Emisi GRK: Pola makan daging menghasilkan 17 kali lebih banyak emisi daripada pola makan vegan.

Pemeliharaan ternak bertanggung jawab atas sedikitnya 51% dari seluruh emisi gas rumah kaca. 

Lahan: Dua hektar, atau empat ekar tanah, bisa menghidupi 1 orang pemakan daging atau 80 vegan. (Wawancara Supreme Master TV bersama guru besar hukum Gary Francione, Universitas Rutgers, AS, 2008)
Dengan dua hektar tanah, kita bisa menghidupi 1 orang pemakan dag ng atau 80 vegan yang sehat.
Air: Seorang pemakan daging memakai air 15 kali lebih banyak daripada yang dipakai seorang vegan.

  • 200.000 liter untuk menghasilkan 1 kilogram daging sapi Dibanding
  • 2.000 liter = 1 kilogram kedelai
  • 900 liter = 1 kilogram gandum
  • 650 liter = 1 kilogram jagung
Bahan bakar fosil: Produk hewani membutuhkan 11 kali lebih banyak bahan bakar fosil-melepaskan CO2 11 kali lebih banyak.
Makanan: Satu kilogram daging sapi membutuhkan 7 kilogram biji-bijian untuk memproduksinya.

BIAYA SATU HAMBURGER

  • 5 meter persegi (55 kaki persegi) hutan hujan tropis dihancurkan.
  • 23.000 liter (6.000 gallon) air bersih (mandi tiap hari selama 14 bulan).
  • 1,8 kilogram (4 pon) biji-bijian dikonsumsi oleh sapi (sekitar 3 balok roti utuh).
  • 4 kilogram (8,75 pon) humus lenyap (Humus = lapisan tanah subur).
  • 30 spesies tumbuhan, 100 spesies serangga, dan lusinan burung, mamalia hilang.
Mari selamatkan bumi dengan meminimalisasi konsumsi daging dan mulai beralih ke vegetarian 
 Sumber: COP16 Konferensi Perubahan Iklim Cancun, Meksiko - 18 Desember, 2010 oleh Maha Guru Ching Hai 

Anda dapat mengetahui lebih dalam dengan mengunjungi situs-situs berikut:
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Rino Safrizal
Jejaring Kimia Updated at: April 17, 2011

April 05, 2011

KISI-KISI SOAL KIMIA UN SMA 2010/2011

April 05, 2011
Bagi Anda yang ingin mendownload kisi-kisi soal ujian nasional tahun pelajaran 2010/2011 mata pelajaran kimia dapat diperoleh di sini atau langsung melalui link ini. Kisi-kisi soal Insya Allah mengacu pada Standar Kompetensi Lulusan tahun 2010/2011 dan referensi soal kimia 4 (empat) tahun terakhir. Semoga bermanfaat..!!!
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Rino Safrizal
Jejaring Kimia Updated at: April 05, 2011

April 04, 2011

FLUORITE [ Halides ]

April 04, 2011

CaF2, calcium Fluoride
As a flux (hence the name) in iron smelting, a rare gemstone, a source of fluorine, as special optical lenses and a popular mineral specimen
Fluorite is a mineral with a veritable bouquet of brilliant colours. Fluorite is well known and prized for its glassy luster and rich variety of colours. The range of common colours for fluorite starting from the hallmark colour purple, then blue, green, yellow, colourless, brown, pink, black and reddish orange is amazing and is only rivaled in colour range by quartz. Intermediate pastels between the previously mentioned colours are also possible. It is easy to see why fluorite earns the reputation as "The Most Colorful Mineral in the World".
The many colours of fluorite are truly wonderful. The rich purple colour is by far fluorite’s most famous and popular colour. It easily competes with the beautiful purple of amethyst. Often specimens of fluorite and amethyst with similar shades of purple are used in mineral identification classes to illustrate the folly of using colour as the sole means to identify minerals.

The blue, green and yellow varieties of fluorite are also deeply coloured, popular and attractive. The colourless variety is not as well received as the coloured varieties, but their rarity still makes them sought after by collectors. A brown variety found in Ohio and elsewhere has a distinctive iridescence that improves an otherwise poor colour for fluorite. The rarer colours of pink, reddish orange (rose) and even black are usually very attractive and in demand.

Most specimens of fluorite have a single colour, but a significant percentage of fluorites have multiple colours and the colours are arranged in bands or zones that correspond to the shapes of fluorite’s crystals. In other words, the typical habit of fluorite is a cube and the colour zones are often in cubic arrangement. The effect is similar to phantomed crystals that appear to have crystals within crystals that are of differing colours. A fluorite crystal could have a clear outer zone allowing a cube of purple fluorite to be seen inside. Sometimes the less common habits such as a coloured octahedron are seen inside of a colourless cube. One crystal of fluorite could potentially have four or five different colour zones or bands.

To top it all off, fluorite is frequently fluorescent and, like its normal light colours, its fluorescent colours are extremely variable. Typically it fluoresces blue but other fluorescent colours include yellow, green, red, white and purple. Some specimens have the added effect of simultaniously having a different colour under longwave UV light from its colour under shortwave UV light. And some will even demonstrate phosphorescence in a third colour. That’s four possible colour luminescence in one specimen. If you count the normal light colour too. The blue fluorescence has been attributed to the presence of europium ions (Eu+2). Yttrium is the activator for the yellow fluorescence. Green and red fluorescent activation is not exactly pinned down as of yet, but may be due to the elements already mentioned as well as other rare earth metals; also manganese, uranium or a combination of these. Even unbonded fluorine trapped in the structure has been suggested. The word fluorescent was derived from fluorite since specimens of fluorite were some of the first fluorescent specimens ever studied. The naming followed the naming precedence set by opalescence from opal; ergo fluorescence from fluorite.

Another unique luminescent property of fluorite is its thermoluminescence. Thermoluminescence is the ability to glow when heated. Not all fluorites do this, in fact it is quite a rare phenomenon. A variety of fluorite known as "chlorophane" can demonstrate this property very well and will even thermoluminesce while the specimen is held in a person’s hand activated by the person’s own body heat (of course in a dark room, as it is not bright enough to be seen in daylight). The thermoluminescence is green to blue-green and can be produced on the coils of a heater or electric stove top. Once seen, the glow will fade away and can no longer by seen in the same specimen again. It is a one shot deal. Chlorophane (which means to show green) is found in very limited quantities at Amelia Court House, Virginia; Franklin, New Jersey and the Bluebird Mine, Arizona, USA; Gilgit, Pakistan; Mont Saint-Hilaire, Quebec, Canada and at Nerchinsk in the Ural Mountains, Russia.

Fluorite has other qualities besides its great colour assortments that make it a popular mineral. It has several different crystal habits that always produce well formed, good, clean crystals. The cube is by far the most recognized habit of fluorite followed by the octahedron which is believed to form at higher temperatures than the cube. Although the cleavage of fluorite can produce an octahedral shape and these cleaved octahedrons are popular in rock shops the world over, the natural (e.g. uncleaved) octahedrons are harder to find.

A rarer habit variety is the twelve sided dodecahedron however it is never seen by itself and usually modifies the cubic crystals by replacing the edges of the cube with one flat face of a dodecahedron. The tetrahexahedron is a twenty four sided habit that is also seen modifying the cubic habit. But instead of one face replacing each cubic edge, two faces modify the cube’s edges. Occasionally combinations of a cube, dodecahedron and tetrahexahedron are seen producing an overall cubic crystal with no less that three minor parallel faces replacing each cubic edge. A fifth form is the hexoctahedron which modifies the cube by placing six very minor faces at each corner of the cube. Twinning is also common in fluorite and symmetrical penetration twins, especially from Cumberland England are much sought after by collectors.

Fluorite, as mention above, has octahedral cleavage. This means that it has four identical directions of cleavage and when cleaved in the right ways can produce a perfect octahedral shape. Many thousands of octahedrons are produced from massive or large undesirable crystals of fluorite (hopefully.) and are sold in rock shops and museum gift shops at a small cost. Fluorite mine workers are reported to sit down at lunch breaks and cleave the octahedrons for the extra cash. The octahedrons are very popular due to their attractive colours, clarity, "diamond-shaped" and low costs, but to a serious collector they are nothing more than "cleavage fragments".

Fluorite not only is attractive in its own right but is often associated with other attractive minerals. Fluorite crystals will frequently accompany specimens of silver gray galena, brassy yellow pyrite, chalcopyrite or marcasite, golden barite, black sparkling sphalerite, intricately crystallized calcite and crystal clear quartz, even amethyst.

The origin of the word fluorite comes from the use of fluorite as a flux in steel and aluminium processing. It was originally referred to as fluorospar by miners and is still called that today. Fluorite is also used as a source of fluorine for hydrofluoric acid and fluorinated water. The element fluorine also gets its name from fluorite, fluorines only common mineral. Other uses of fluorite include an uncommon use as a gemstone (low hardness and good cleavage reduce its desirability as a gemstone), ornamental carvings (sometimes misleadingly called Green quartz) and special optical uses.

Fluorite is the most popular mineral for mineral collectors in the world, second only to quartz. Every mineral collection owned by even the newest and youngest of mineral collectors must have a specimen of fluorite. Fluorite is by far one of the most beautiful and interesting minerals available on the mineral markets.

Physical Characteristics

Colour: extremely variable and many times can be an intense purple, blue, green or yellow; also colourless, reddish orange, pink, white and brown. A single crystal can be multi-coloured
Luster: vitreous
Transparency: Crystals are transparent to translucent
Crystal System: Isometric; 4/m bar 3 2/m
Crystal Habits: include the typical cube and to a lesser extent, the octahedron as well as combinations of these two and other rarer isometric habits. Always with equant crystals; less common are crusts and botryoidal forms. Twinning also produces penetration twins that look like two cubes grown together
Cleavage: perfect in 4 directions forming octahedrons
Fracture: irregular and brittle
Hardness: 4
Specific Gravity: 3.1+ (average)
Streak: white
Other: Often fluorescent blue or more rarely green, white, red or violet and may be thermoluminescent, phosphorescent and triboluminescent
Associated Minerals: include calcite, quartz, willemite, barite, witherite, apatite, chalcopyrite, galena, sphalerite, pyrite and other sulfides
Major Occurrences: in addition to those mentioned above Cumberland, England; Spain; China; Brazil; Morocco; Bancroft, Ontario, Canada; Naica, Chihuahua, Mexico; Germany; Elmwood, Tennessee; Rosiclare, Illinois; Fort Wayne, Indiana; Pugh Quarry and Wood County, Ohio; Nancy Hanks Mine, Colorado and many other USA localities as well as many other localities from around the world
Best Indicators: crystal habit, colour zoning, hardness (harder than calcite, but softer than quartz or apatite), fluorescence and especially the octahedral cleavage
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Rino Safrizal
Jejaring Kimia Updated at: April 04, 2011

SPHALERITE/ZINC BLENDE [ Sulfides : Sphalerite ]

April 04, 2011

Zn, Fe)S, zinc iron Sulfide
Major ore of zinc, rarely cut into gemstones, mineral specimen
Sphalerite (which is also known as Blende), is an important ore of zinc and can make a rather attractive cabinet specimen as well. It can have excellent luster and associates with many beautifully coloured minerals making it one of the best enhancers of many fine mineral specimens.

Sphalerite is one of the very few minerals that has a total of six directions of cleavage. If all of them were to be perfectly cleaved on a single crystal it would form a rhombic dodecahedron. Identifying all six directions in a single cleaved crystal is quite difficult due to the multiple twinning and the many directions. Only the fact that there is abundant cleavage at different directions can easily be seen in most cleaved specimens.
Sphalerite can be difficult to identify because of its variable luster, colour, abundant but obscured cleavage and crystal habits. So difficult was sphalerite for miners to distinguish from more valuable minerals such as galena, acanthite and tetrahedrite, that they named it sphalerite which is Greek for treacherous rock and blende is German for blind or deceiving.

The luster of sphalerite is truly its best attribute. It typically has a nice adamantine luster that really sparkles owing to its unusually high index of refraction and a fire greater than diamond’s. Specimens of sphalerite are usually adorned with hundreds of small sparkling faces. Groups of faces can be symmetrically oriented into several different directions so that as a particularly gifted specimen is turned with respect to a viewer they are treated to several episodes of multiple and bright flashes. Transparent sphalerite has been cut for gemstones but its cleavage and softness limit its use as a gemstone to collectors only.

The twinning of sphalerite is also special. It can form a spinel twin which is a specialty of the mineral spinel. The spinel twin is where a tetrahedral crystal is twisted in the middle so that three points of the tetrahedron are in alignment with the other three points. These crystals are not usually completely developed in sphalerite but the indentations that the twinning causes are usually seen on some crystals in almost every specimen. A twin type for some reason called a "chicken twin" or "hen" forms a sort-of football shaped twin.

Sphalerite is a polymorph with two minerals, wurtzite and matraite. The three are called polymorphs (meaning many shapes) because although they have the same chemistry, (Zn, Fe)S or zinc iron sulfide, they have different structures and therefore different shapes. Sphalerite is by far the more common mineral of the three.
Sphalerite’s structure is analogous to the diamond structure. If every other carbon in the diamond structure is replaced by a sulfur atom and the remaining carbons are replaced with either a zinc or an iron atom then basically the mineral is sphalerite.

Sphalerite is by no doubt the most important ore of zinc, an industrially and at times strategically important metal. Other zinc ores include hemimorphite, smithsonite, willemite, franklinite and zincite. Although its importance as an ore of zinc is undisputed, it is a very attractive and a very interesting mineral for collectors as well.

Physical Characteristics

Colour: typically black but can be brown, yellow, reddish, green, and less commonly white or colourless
Luster: adamantine or resinous or submetallic to earthy in massive forms
Transparency: crystals are transparent to translucent
Crystal System: isometric; bar 4 3m
Crystal Habits: can be complicated with the rhombic dodecahedron, tetrahedron and combinations of these having cubic and tristetrahedron faces giving the crystals multiple faces of often indistinct forms. To add more confusion to the indistinct crystals, twinning is common and sometimes pervasive. Massive forms are common and can be granular, earthy, botryoidal, concretionary and fibrous. An aggregate of botryoidal crusts with layers of wurtzite and galena is called "Schalenblende" is sometimes cut and polished as an ornamental stone
Cleavage: perfect in six directions forming dodecahedrons
Fracture: conchoidal, but rarely seen because of frequent cleavage
Hardness: 3.5 - 4
Specific Gravity: approx. 4.0 (heavier than average, but light when compared to most metallic minerals)
Streak: yellow to light brown (unusually light coloured for a normally dark mineral)
Other: Striations on tetrahedral faces, triboluminescent (meaning it may glow if crushed), an index of refraction of 2.37 - 2.42, a dispersion (fire) of 0.156 and finally sphalerite is pyroelectric (meaning that it forms a slight electrical charge when heated or cooled)
Associated Minerals: almost always include galena, pyrite, fluorite, chalcopyrite, quartz, calcite, magnetite, pyrrhotite and many others
Major Occurrences: include Tri state area near Joplin, Missouri; Rosiclare, Illinois; Elmwood, Tennessee, USA; Broken Hill, Australia; Italy; Spain; Burma; Peru; Morocco; Germany and England
Best Indicators: crystal habits, streak, cleavage, high luster, softness and twinning
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Rino Safrizal
Jejaring Kimia Updated at: April 04, 2011

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