Senin, 12 Juli 2010

Chemistry Teacher


Siapa bilang pelajaran kimia itu sulit....? siapa bilang pelajaran kimia itu tak asik..? siapa bilang belajar kimia tak berguna...? Kunci  dari jawaban atas pertanyaan - pertanyaan itu adalah  rasa ingin tahu  , kesabaran dan ketidak sombongan pada diri orang itu. Banyak orang awam bicara kimia..... maka gambaran mengerikan yang dikepalanya. Orang sombong bicara kimia  maka kemunafikan yang ia katakan.  Belajar kimia berarti belajar sebagian isi kehidupan... kimia tidak akan pernah bisa dibuang dari kehidupan....... Semakin kita tahu dan faham  pengertian dan makna kimia Insyaallah akan semakin hati-hati membawa diri.Contoh kecil persiapan pembelajaran kimia unuk kelas X klik disini

Jumat, 09 Juli 2010

Modul Kimia klas X.

1. Kalian sudah tahu kan, unsur – unsur yang tercantum dalam tabel periodik ada 100an. Bagaimana unsur – unsur tersebut dapat membentuk jutaan senyawa dan bahkan benda yang tak terhitung jenisnya?
Ya, seperti kata – kata dalam buku ini yang jumlahnya ribuan dan membentuk begitu banyak kalimat, hanya terbentuk dari 26 huruf. Demikian juga benda - benda yang ada di bumi tersusun dari hanya sedikit unsur yang kalian kenal. Unsur – unsur ini saling bergabung membentuk senyawa, kumpulan senyawa dan akhirnya benda – benda seperti kertas, gajah dan kalian sendiri.
Mengapa benda – benda ini begitu berbeda? Mengapa belerang sangat rapuh dan tidak dapat ditempa seperti besi? Mengapa lilin meleleh jika dibakar, sedangkan kertas atau kayu tidak? Mengapa air dapat membeku menjadi es? Mengapa kita menggunakan grafit untuk pensil, bukan arang atau intan padahal ketiganya sama – sama karbon?
Sama seperti, setiap kata dan kalimat yang memberi arti berbeda tergantung pada bagaimana kalian merangkainya, sifat – sifat benda atau senyawa juga tergantung pada unsur dan bagaimana cara unsur itu bergabung. Dalam bab ini kita akan mempelajari mengapa dan bagaimana setiap unsur bergabung membentuk senyawa. 
Untuk membaca lengkap bahan ajar kimia "Ikatan Kimia" dapat Klik disini


2. Saat Kalian melihat batuan yang tidak biasa, cangkang hewan laut yang bagus, kristal salju, daun yang memerah, karat, plastisin, kuku, rambut, bahkan juga kertas, kapas, sirup, nata de coco, atau compact disk (CD) dan baterei isi ulang, Kalian mungkin pernah bertanya terbuat dari apakah benda – benda ini.
Tahukah Kalian pertanyaan itu telah menggelitik manusia sejak lama. Sejak dulu orang telah bertanya, menduga, dan memperkirakan apa yang menyusun benda – benda di sekitarnya, dan juga tubuhnya sendiri.
Bangsa Yunani kuno percaya bahwa segala sesuatu tersusun atas empat unsur dasar, yaitu air, udara, tanah, dan api. Sifat setiap benda tergantung bagaimana komposisi unsur – unsur ini disusun.
Pada abad ke – 17, seorang ilmuwan Inggris, Robert Boyle, mengemukakan bahwa setiap unsur tersusun atas partikel yang sederhana, dan tidak tersusun atas unsur yang lain. Pernyataan inilah yang mendasari berkembangnya konsep atom, penyusun unsur, hingga sekarang. Kita akan mempelajari bagaimana konsep atom berkembang dari yang paling sederhana hingga konsep yang kita terima sekarang dalam bab ini.
Untuk membaca lengkap bahan ajar Kimia "Struktur atom dan SPU" dapat klik disini   

Selasa, 06 Juli 2010

Herbal


TEH MAHKOTA DEWA Komposisi : 1.Buah Mahkota Dewa (Phaleria Papuana Fructus) 70 % 2.Daun Teh Hijau (Camallia Sinensis Folium) 20 % 3.Benalu Teh (Scumula Atropurpurea Folium) 10 % Insya Allah Bermanfaat mengobati dan mencegah Penyakit : Demam berdarah, Kanker, Liver, Darah Tinggi, Stroke, Jantung, Kencing Manis, Ginjal/Cuci darah, Kegemukan, Batuk, Sesak Napas, Jerawat (Menghaluskan Kulit), Keputihan, Haid Tidak Lancar, Rheumatik, Ambeien, Amandel, Lemah Syahwat, Asam Urat Untuk Segala Umur Perhatian : Wanita Hamil Muda Dilarang Minum Produksi Salama Nusantara Samigaluh, Kulon Progo Yogyakarta Export Quality Mendapatkan Izin Resmi : SK MENKES RI No. 448/3025/IV.2 IZIN EDAR BALAI POM, TR No. 053151771 LOLOS UJI LAB. BALAI POM Tahun 2005 Diawasi oleh Apoteker Alumnus UGM Yogyakarta Sertifikasi Halal MUI No 121 300000 80306 Berat Bersih 130 grams Harga Katalog/Eceran Rp. 25.000,- Harga Hemat Rp. 20.000,- (Min 4 pcs/Hemat 20%) Harga Grosir Rp. 17.000,- (Min 35 pcs/Hemat 30%)

Senin, 05 Juli 2010

Renungan Hati Seorang Guru

Ditengah kesibukanku sebagai seorang Guru aku akan selalu berusaha meningkatkan kemampuan dan profesionalitas seorang Guru.  Ya.... seorang guru yang senantiasa mampu menjawab  dan sekaligus melayani kebutuhan semua umat.  Aku akan selalu ingat ketika Ustad dalam Ta'lim memfatwakan  "Sebaik-baik orang  adalah orang yang semakin banyak mendatangkan manfaat bagi orang lain". Kadang aku merenung sudahkah ada  umat yang merasa mendapat manfaat atas kehadiranku ditengah-tengah mereka...???!!. Marilah saudara-saudaraku kita berlomba beramar ma'ruf nahi munkar... Allah kan Selalu bersama kita, amiin!!!

Jumat, 02 Juli 2010

Biogas


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Pipes carrying biogas (foreground), natural gas and condensate
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel.
One type of biogas is produced by anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material and energy crops.[1] This type of biogas comprises primarily methane and carbon dioxide. The other principal type of biogas is wood gas which is created by gasification of wood or other biomass. This type of biogas is comprised primarily of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane.
The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen. Air contains 21% oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a low-cost fuel in any country for any heating purpose, such as cooking. It can also be used in modern waste management facilities where it can be used to run any type of heat engine, to generate either mechanical or electrical power. Biogas can be compressed, much like natural gas, and used to power motor vehicles and in the UK for example is estimated to have the potential to replace around 17% of vehicle fuel.[2] Biogas is a renewable fuel, so it qualifies for renewable energy subsidies in some parts of the world.

Contents

[hide]

[edit] History

Ancient Persians observed that rotting vegetables produce flammable gas. In 1859 Indians built the first sewage plant in Bombay. Marco Polo has mentioned the use of covered sewage tanks in China. This is believed to go back to 2,000–3,000 years ago in ancient China.[citation needed] This idea for the manufacturing of gas was brought to the UK in 1895 by producing wood gas from wood and later coal. The resulting biogas was used for gas lighting in street lamps and homes.

[edit] Production

Biogas is practically produced as landfill gas (LFG) or digester gas.
A biogas plant is the name often given to an anaerobic digester that treats farm wastes or energy crops.
Biogas can be produced utilizing anaerobic digesters. These plants can be fed with energy crops such as maize silage or biodegradable wastes including sewage sludge and food waste. During the process, an air-tight tank transforms biomass waste into methane producing renewable energy that can be used for heating, electricity, and many other operations that use any variation of an internal combustion engine, such as GE Jenbacher gas engines.[3] There are two key processes: Mesophilic and Thermophilic digestion.[4]
Landfill gas is produced by wet organic waste decomposing under anaerobic conditions in a landfill.[5][6] The waste is covered and mechanically compressed by the weight of the material that is deposited from above. This material prevents oxygen exposure thus allowing anaerobic microbes to thrive. This gas builds up and is slowly released into the atmosphere if the landfill site has not been engineered to capture the gas. Landfill gas is hazardous for three key reasons. Landfill gas becomes explosive when it escapes from the landfill and mixes with oxygen. The lower explosive limit is 5% methane and the upper explosive limit is 15% methane.[7] The methane contained within biogas is 20 times more potent as a greenhouse gas than carbon dioxide. Therefore uncontained landfill gas which escapes into the atmosphere may significantly contribute to the effects of global warming. In addition landfill gas' impact in global warming, volatile organic compounds (VOCs) contained within landfill gas contribute to the formation of photochemical smog.

[edit] Composition

Typical composition of biogas[8]
Compound Chem  %
Methane CH4 50–75
Carbon dioxide CO2 25–50
Nitrogen N2 0–10
Hydrogen H2 0–1
Hydrogen sulfide H2S 0–3
Oxygen O2 0–2
The composition of biogas varies depending upon the origin of the anaerobic digestion process. Landfill gas typically has methane concentrations around 50%. Advanced waste treatment technologies can produce biogas with 55–75% CH4 [9] or higher using in situ purification techniques[10] As-produced, biogas also contains water vapor, with the fractional water vapor volume a function of biogas temperature; correction of measured volume for water vapor content and thermal expansion is easily done via algorithm.[11]
In some cases biogas contains siloxanes. These siloxanes are formed from the anaerobic decomposition of materials commonly found in soaps and detergents. During combustion of biogas containing siloxanes, silicon is released and can combine with free oxygen or various other elements in the combustion gas. Deposits are formed containing mostly silica (SiO2) or silicates (SixOy) and can also contain calcium, sulfur, zinc, phosphorus. Such white mineral deposits accumulate to a surface thickness of several millimeters and must be removed by chemical or mechanical means.
Practical and cost-effective technologies to remove siloxanes and other biogas contaminants are currently available.[12]

[edit] Applications

Biogas can be utilized for electricity production on sewage works,[13] in a CHP gas engine, where the waste heat from the engine is conveniently used for heating the digester; cooking; space heating; water heating; and process heating. If compressed, it can replace compressed natural gas for use in vehicles, where it can fuel an internal combustion engine or fuel cells and is a much more effective displacer of carbon dioxide than the normal use in on-site CHP plants.[2]
Methane within biogas can be concentrated via a biogas upgrader to the same standards as fossil natural gas, and becomes biomethane. If the local gas network allows for this, the producer of the biogas may utilize the local gas distribution networks. Gas must be very clean to reach pipeline quality, and must be of the correct composition for the local distribution network to accept. Carbon dioxide, water, hydrogen sulfide and particulates must be removed if present. If concentrated and compressed it can also be used in vehicle transportation. Compressed biogas is becoming widely used in Sweden, Switzerland, and Germany. A biogas-powered train has been in service in Sweden since 2005.[14][15]
Biogas has also powered automobiles. In 1974, a British documentary film entitled Sweet as a Nut detailed the biogas production process from pig manure, and how the biogas fueled a custom-adapted combustion engine.[16][17]

[edit] Scope and potential quantities

In the UK, sewage gas electricity production is tiny compared to overall power consumption - a mere 80 MW of generation, compared to 70 GW on the grid. Estimates vary but could be a considerable fraction from digestion of.[18][clarification needed]
In the United States, in 2003, consumed 147 trillion btu of energy from "landfill gas", about 0.6% of total U.S. natural gas consumption.[19] Methane biogas derived from cow manure is also being tested in the U.S. According to a 2008 study, collected by the Science and Children magazine, methane biogas from cow manure, also known as cow power, would be sufficient to produce 100 billion kilowatt hours enough to power millions of homes across America. Furthermore, methane biogas has been tested to prove that it can reduce 99 million metric tons of greenhouse gas emissions or about 4% of the greenhouse gases produced by the United States.[20]
In 2007 an estimated 12,000 vehicles were being fueled with upgraded biogas worldwide, mostly in Europe.[19]

[edit] In developing nations

Domestic biogas plants convert livestock manure and night soil into biogas and slurry, the fermented manure. This technology is feasible for small holders with livestock producing 50 Kg manure per day, an equivalent of about 6 pigs or 3 cows. This manure has to be collectable to mix it with water and feed it into the plant. Toilets can be connected. Another precondition is the temperature that affects the fermentation process. With an optimum at 36 C° the technology especially applies for those living in a (sub) tropical climate. This makes the technology for small holders in developing countries often suitable.

Simple sketch of household biogas plant
Depending on size and location, a typical brick made fixed dome biogas plant can be installed at the yard of a rural household with the investment between 300 to 500 US $ in Asian countries and up to 1400 US $ in the African context. A high quality biogas plant needs minimum maintenance costs and can produce gas for at least 15–20 years without major problems and re-investments. For the user, biogas provides clean cooking energy, reduces indoor air pollution and reduces the time needed for traditional biomass collection, especially for women and children. The slurry is a clean organic fertilizer that potentially increases agricultural productivity.
Domestic biogas technology is a proven and established technology in many parts of the world, especially Asia.[21] Several countries in this region have embarked on large-scale programmes on domestic biogas, such as China[22] and India. The Netherlands Development Organisation, SNV,[23] supports national programmes on domestic biogas that aim to establish commercial-viable domestic biogas sectors in which local companies market, install and service biogas plants for households. In Asia, SNV is working in Nepal,[24] Vietnam,[25] Bangladesh,[26] Cambodia,[27] Lao PDR,[28] Pakistan[29] and Indonesia,[30] and in Africa in Rwanda,[31] Senegal, Burkina Faso, Ethiopia,[32] Tanzania,[33] Uganda and Kenya.

[edit] Rural Dung Sui Gas (Pakistan)/Deenabandhu Model (India)

In Pakistan and India biogas produced from the anaerobic digestion of manure in small-scale digestion facilities is called gobar gas; it is estimated that such facilities exist in over two million households in India and in hundreds of thousands in Pakistan, particularly North Punjab, due to the thriving population of lifestock . The digester is an airtight circular pit made of concrete with a pipe connection. The manure is directed to the pit, usually directly from the cattle shed. The pit is then filled with a required quantity of wastewater. The gas pipe is connected to the kitchen fireplace through control valves. The combustion of this biogas has very little odour or smoke. Owing to simplicity in implementation and use of cheap raw materials in villages, it is one of the most environmentally sound energy sources for rural needs. One type of these system is the Sintex Digester. Some designs use vermiculture to further enhance the slurry produced by the biogas plant for use as compost.[34]
The Deenabandhu Model is a new biogas-production model popular in India. (Deenabandhu means "friend of the helpless.") The unit usually has a capacity of 2 to 3 cubic metres. It is constructed using bricks or by a ferrocement mixture. The brick model costs approximately 18,000 rupees and the ferrocment model 14,000 rupees, however India's Ministry of Non-conventional Energy Sources offers a subsidy of up to 3,500 rupees per model constructed.[citation needed]

[edit] Legislation

The European Union presently has some of the strictest legislation regarding waste management and landfill sites called the Landfill Directive.[citation needed] The United States legislates against landfill gas as it contains VOCs. The United States Clean Air Act and Title 40 of the Code of Federal Regulations (CFR) requires landfill owners to estimate the quantity of non-methane organic compounds (NMOCs) emitted. If the estimated NMOC emissions exceeds 50 tonnes per year the landfill owner is required to collect the landfill gas and treat it to remove the entrained NMOCs. Treatment of the landfill gas is usually by combustion. Because of the remoteness of landfill sites it is sometimes not economically feasible to produce electricity from the gas. However, countries such as the United Kingdom and Germany now has legislation in force that provide farmers with long term revenue and energy security.[35][36]

[edit] Biogas upgrading

Raw biogas produced from digestion is roughly 60% methane and 29% CO2 with trace elements of H2S, and is not high quality enough if the owner was planning on selling this gas or using it as fuel gas for machinery. The corrosive nature of H2S alone is enough to destroy the internals of expensive plant. The solution is the use of a biogas upgrading or purification process whereby contaminants in the raw biogas stream are adsorbed or scrubbed, leaving 98% methane per unit volume of gas. There are four main methods of biogas upgrading, these include water washing, pressure swing adsorption, selexol adsorption and chemical treatment.[37] The most prevalent method is water washing where high pressure gas flows into a column where the carbon dioxide and other trace elements are scrubbed by cascading water running counter-flow to the gas. This arrangement can deliver 98% methane with manufacturers guaranteeing maximum 2% methane loss in the system. It takes roughly between 3-6% of the total energy output in gas to run a biogas upgrading system.

[edit] Biogas gas-grid injection

Gas-grid injection is the injection of biogas into the methane grid (natural gas grid). Injections includes biogas:[38] until the breakthrough of micro combined heat and power two-thirds of all the energy produced by biogas power plants was lost (the heat), using the grid to transport the gas to customers, the electricity and the heat can be used for on-site generation [39] resulting in a reduction of losses in the transportation of energy as typical energy losses in natural gas transmission systems range from 1–2% the current energy losses on a large electrical system range from 5–8%[40].