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Minggu, 25 Maret 2012

GOLONGAN 2


Beryllium
  • X-ray windows (berllium transmits X-rays 17 times better than aluminium
  • as a 2% alloy with nickel for springs, electrodes and nonsparking tools
  • berllium (2%) alloyed with copper gives a hard strong alloy with high resistance to wear used in gyroscopes, computer parts, and instruments (desirable lightness, stiffness)
  • alloys are used as a structural material for high performance aircraft, missiles, spacecraft (such as the USA space shuttle), and communication satellites.
  • ceramics
  • as a moderator in nuclear reactions since it is a highly effective moderator and reflector for neutrons
  • the oxide is used in the nuclear industry
 Magnesium
  • used in flares and pyrotechnics, including incendiary bombs. It was used in flash photography,
  • it is lighter than aluminium, and is used in alloys used for aircraft, car engine casings, and missile construction
  • it is used a reducing agent for the production of uranium and other metals from their salts
  • the hydroxide (milk of magnesia), chloride, sulphate (Epsom salts), and the citrate are used in medicine
  • magnesium oxide is refractory and used as bricks and liners in furnaces
  • used to make organomagnesium compounds (Grignard reagents), useful in organic synthesis
  • used in computers for radio-frequency shielding
 Calcium
  • reducing agent for the preparation of metals such as thorium, uranium, zirconium, etc.
  • deoxidiser, desulphurizer, or decarbonizer for various alloys
  • alloys of calcium with agent for aluminium, beryllium, copper, lead, and magnesium have some useful properties
  • "getter" for residual gases in vacuum tubes, etc.
  • quicklime (CaO) is made by heating limestone (CaCO3) and changes into slaked lime, Ca(OH)2, on the addition of water. It is a cheap base for the chemical industry with many uses.
  • calcium from limestone is a component of Portland cement. Mixed with sand it hardens as mortar and plaster while taking up carbon dioxide from the air
  • the solubility of the carbonate in water containing carbon dioxide results in stalactites and stalagmites (Cheddar Gorge) and hardness in water.
 Strontium
  • fireworks (red flame), flares
  • 90Sr is a radioactive isotope produced by nuclear fallout. 90Sr has the potential for use as lightweight nuclear producing electricity
  • used to produce glass for colour television tubes
  • refining zinc
  • optical materials
 Barium
  • the sulphate, as permanent white or blanc fixe, is used in paint, in X-ray diagnostic work (BaSO4)
  • glassmaking
  • barite is extensively used as a weighting agent in oil well drilling fluids, and in making rubber
  • the carbonate is a rat poison
  • the nitrate and chlorate give green colours (CARE!) in pyrotechnics
  • sulphide is a white pigment
  • making rubber
  • rat poison
 Radium
  • self-luminous paints
  • neutron sources
  • medical uses for the treatment of conditions such as cancer (now being replaced by 60Co sources)

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GOLONGAN 1


Hydrogen (H)
One of hydrogen's isotopes, tritium (3H) is radioactive. Tritium is produced in nuclear reactors and is used in the production of the hydrogen bomb. It is also used as a radioactive agent in making luminous paints and as a tracer isotope.
  • commercial fixation of nitrogen from the air in the Haber ammonia process
  • hydrogenation of fats and oils
  • methanol production, in hydrodealkylation, hydrocracking, and hydrodesulphurization
  • rocket fuel
  • welding
  • production of hydrochloric acid
  • reduction of metallic ores
  • for filling balloons (hydrogen gas much lighter than air; however it ignites easily)
  • liquid H2 is important in cryogenics and in the study of superconductivity since its melting point is only just above absolute zero

Lithium (Li)
Both lithium metal and its compounds have many uses.
  • lithium stearate is mixed with oils to make all-purpose and high-temperature lubricants
  • lithium hydroxide is used to absorb carbon dioxide in space vehicles
  • lithium is alloyed with aluminium, copper, manganese, and cadmium to make high perfomance alloys for aircraft
  • Bahnmetall consists of lead containing 0.04% lithium, 0.7% calcium and 0.6% sodium is harder than pure lead and was used for railroad car bearings in Germany.
  • compounds such as LiAlH4 and organolithium reagents (LiMe, LiPh, etc.) are very important as reagents in organic chemistry
  • lithium metal has the highest specific heat of any solid element and so heat transfer applications
  • various nuclear applications
  • lithium is sometimes used as battery anode material (high electrochemical potential) and lithium compounds are used in dry cells and storage batteries
  • lithium is used in the manufacture of special high strength glasses and ceramics
  • sometimes, lithium-based compounds such as lithium carbonate (Li2CO3) are used as drugs to treat manic-depressive disorders.
 Sodium (Na)
  • sodium metal is used in the preparation of tetraethyl lead, PbEt4, an important anti-knock reagent in leaded petrol (gasoline) - fortunately being phased out in many countries because of lead pollution problems
  • sodium metal is used in the preparation of titanium metal from TiCl4
  • the metal is used in the manufacture of sodamide, sodium cyanide, sodium peroxide, and sodium hydride
  • the metal is used in the reduction of organic esters, and in the preparation of organic compounds
  • the alloy with potassium, NaK, is an important heat transfer agent and a good chemical reducing agent (as some proportions of Na and K are liquid at room temperature).
  • sodium compounds including "common salt" (sodium chloride, NaCl), "soda ash" (sodium carbonate, Na2CO3), "baking soda" (sodium bicarbonate, NaHCO3, "bicarb"), and "caustic soda" (sodium hydroxide, NaOH), are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries
  • sodium vapour is used in lamps for street lighting
  • table salt - don't use too much!

Potassium (K)
  • The superoxide KO2 is used in breathing apparatus where moisture in the breath and carbon dioxide reacts with it to release oxygen [2KO2 + H2O + 2CO2 → 2KHCO3 + O2 ]
  • the alloy of potassium with sodium (NaK) is used as a heat-transfer medium in nuclear reactors. The alloy is liquid at ambient temperature and is a good reducing agent in the chemistry laboratory
  • fertilizers - usually as the chloride, sulphate, nitrate, or carbonate
  • possium nitrate, KNO3, and potassium chlorate, KClO3, are used in fireworks
  • potassium bromide, KBr, was used as an antaphrodisiac - oh dear!
  • potassium permanganate, KMnO4, is an important oxidizing agent
  • low-sodium salt
  • potassium hydroxide is used in the preparation of potassium phosphates for liquid detergents

Rubidium (Rb)
  • rubidium is easily ionized, and so has possible use in "ion engines" for space vehicles (but caesium is somewhat more efficient)
  • used as a "getter" in vacuum tubes
  • photocell component
  • used for making special glasses
  • RbAg4I5 has the highest room temperature conductivity of any known ionic crystal. At ambient temperature, its conductivity is about the same as dilute sulphuric acid, suggesting uses in thin film batteries

Caesium (Cs)
  • the metal can be used in ion propulsion systems. Although not usable in the earth's atmosphere, 1 kg of caesium in outer space could propel a vehicle 140 times as far as the burning of the same amount of any known liquid or solid. It is more efficient than rubidium.
  • used in atomic clocks
  • because of its high oxygen affinity, the metal is used as a "getter" in electron tubes
  • used in photoelectric cells and vacuum tubes
  • IR lamps

Francium (Fr)
  • Francium has no uses.
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Rabu, 14 Maret 2012

SCRAMBLE ASAM BASA

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JIGSAW ASAM BASA

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Games Larutan

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TTS LARUTAN 2

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TTS LARUTAN

Silahkan di kerjakan:

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TTS LARUTAN.htm
TTS LARUTAN.zip
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Minggu, 11 Maret 2012

ASAM DAN BASA

Ayo Siapa Tahu? Apa itu ASAM? Apa itu BASA? Bagaimana ya kalau ASAM DAN BASA bila dicampurkan? To Be Continued.......

Teori Asam Basa


A. MENURUT ARRHENIUS

Menurut teori Arrhenius, zat yang dalam air menghasilkan ion H + disebut asam danbasa adalah zat yang dalam air terionisasi menghasilkan ion OH - .
HCl --> H + + Cl -
NaOH --> Na + + OH -
Meskipun teori Arrhenius benar, pengajuan desertasinya mengalami hambatan berat karena profesornya tidak tertarik padanya. Desertasinya dimulai tahun 1880, diajukan pada 1883, meskipun diluluskan teorinya tidak benar. Setelah mendapat bantuan dari Van’ Hoff dan Ostwald pada tahun 1887 diterbitkan karangannya mengenai asam basa. Akhirnya dunia mengakui teori Arrhenius pada tahun 1903 dengan hadiah nobel untuk ilmu pengetahuan.
Sampai sekarang teori Arrhenius masih tetap berguna meskipun hal tersebut merupakan model paling sederhana. Asam dikatakan kuat atau lemah berdasarkan daya hantar listrik molar. Larutan dapat menghantarkan arus listrik kalau mengandung ion, jadi semakin banyak asam yang terionisasi berarti makin kuat asamnya. Asam kuat berupa elektrolit kuat dan asam lemah merupakan elektrolit lemah. Teori Arrhenius memang perlu perbaikan sebab dalam lenyataan pada zaman modern diperlukan penjelasanyang lebih bisa diterima secara logik dan berlaku secara umum. Sifat larutan amoniak diterangkan oleh teori Arrhenius sebagai berikut:
NH 4 OH --> NH 4 + + OH -
Jadi menurut Svante August Arrhenius (1884) asam adalah spesi yang mengandung H + dan basa adalah spesi yang mengandung OH -, dengan asumsi bahwa pelarut tidak berpengaruh terhadap sifat asam dan basa.
Sehingga dapat disimpulkan bahwa:

Asam ialah senyawa yang dalam larutannya dapat menghasilkan ion H + .
Basa ialah senyawa yang dalam larutannya dapat menghasilkan ion OH - .
Contoh:
1) HCl(aq) --> H + (aq) + Cl - (aq)
2) NaOH(aq) --> Na + (aq) + OH - (aq)

 
























B. MENURUT BRONSTED-LOWRY
Asam ialah proton donor, sedangkan basa adalah proton akseptor.

Teori asam basa dari Arrhenius ternyata tidak dapat berlaku untuk semua pelarut, karena khusus untuk pelarut air. Begitu juga tidak sesuai dengan reaksi penggaraman karena tidak semua garam bersifat netral, tetapi ada juga yang bersifat asam dan ada yang bersifat basa.
Konsep asam basa yang lebih umum diajukan oleh Johannes Bronsted, basa adalah zat yang dapat menerima proton. Ionisasi asam klorida dalam air ditinjau sebagai perpindahan proton dari asam ke basa.
HCl + H 2 O --> H 3 O + + Cl -
Demikian pula reaksi antara asam klorida dengan amoniak, melibatkan perpindahan proton dari HCl ke NH 3 .
HCl + NH 3 NH 4 + + Cl -
Ionisasi asam lemah dapat digambarkan dengan cara yang sama.
HOAc + H 2 O H 3 O + + OAc -
Pada tahun 1923 seorang ahli kimia Inggris bernama T.M. Lowry juga mengajukan hal yang sama dengan Bronsted sehingga teori asam basanya disebut Bronsted-Lowry. Perlu diperhatikan disini bahwa H + dari asam bergabung dengan molekul air membentuk ion poliatomik H 3 O + disebut ion Hidronium.
Reaksi umum yang terjadi bila asam dilarutkan ke dalam air adalah:
HA + H 2 O H 3 O + + A -
asam basa asam konjugasi basa konjugasi
Penyajian ini menampilkan hebatnya peranan molekul air yang polar dalam menarik proton dari asam.
Perhatikanlah bahwa asam konjugasi terbentuk kalau proton masih tinggal setelah asam kehilangan satu proton. Keduanya merupakan pasangan asam basa konjugasi yang terdi dari dua zat yang berhubungan satu sama lain karena pemberian proton atau penerimaan proton. Namun demikian disosiasi asam basa masih digunakan secara Arrhenius, tetapi arti yang sebenarnya harus kita fahami.
Johannes N. Bronsted dan Thomas M. Lowry membuktikan bahwa tidak semua asam mengandung ion H + dan tidak semua basa mengandung ion OH - .
Bronsted – Lowry mengemukakan teori bahwa asam adalah spesi yang memberi H + ( donor proton ) dan basa adalah spesi yang menerima H + (akseptor proton). Jika suatu asam memberi sebuah H + kepada molekul basa, maka sisanya akan menjadi basa konjugasi dari asam semula. Begitu juga bila basa menerima H + maka sisanya adalah asam konjugasi dari basa semula.
Teori Bronsted – Lowry jelas menunjukkan adanya ion Hidronium (H 3 O + ) secara nyata.
Contoh:
HF + H 2 O ⇄ H 3 O + + F -
Asam basa asa m konjugasi basa konjugasi

HF merupakan pasangan dari F - dan H 2 O merupakan pasangan dari H 3 O + .
Air mempunyai sifat ampiprotik karena dapat sebagai basa dan dapat sebagai asam.
HCl + H 2 O --> H 3 O + + Cl -
Asam Basa
NH 3 + H 2 O ⇄ NH 4 + + OH -
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Jumat, 02 Maret 2012

UJIAN SEMESTER VI KELAS XII 2012

FOR XII TKJ2 DAN TKJ3
SMK NEGERI 1 BANGKINANG
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PREDIKSI UAS KIMIA KELAS XII

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KOSENTRASI LARUTAN

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UAS PRAKTEK KIMIA B 2012

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UAS PRAKTEK KIMIA A 2012

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KUMPULAN SOAL KIMIA

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Ulangan Harian 1. Larutan Elekrolit dan Kosentrasi Larutan

For: Kelas XI SMK Negeri 1 Bangkinang

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