tgl 12 jan 2010(selasa)
hari ini q udah ujian kimdas,,,
tp soal na susah bgtz,,,,mga ja dpt nilai gede,,
n besuk ujian bhs inggris yg lebih sulit lg,,,,,
karna masih berhubungan dg kimia jg,,,ufff ,..............
capek deh,,
tapi q harus ttep semangad dlm menjalani na.....
coz udah pilihan q tuk ngambil jurusan kimia,,,hiks hiks hiks,,,,,,
Senin, 11 Januari 2010
Sabtu, 09 Januari 2010
chemical changes and physical changes
Physical changes are not marked with the formation of new substances. While chemical changes indicated by the formation of new substances.
More physical changes we know as being a change agent. In the form of the substance changes, no new substance is formed. Although the substance has changed his form but still has a chemical formula of the same molecule. Various kinds of physical changes:
1. Melting: changing the form of a substance from solid to liquid.
2. Yawning: a substance changes from liquid form to gas.
3. Sublime: changes in gas form to the substance of the solid / vice versa.
4. Condense: changes in substance from the gas form into the liquid.
5. Frozen: changes in substance from liquid form to solid.
Change the ice melts into water are examples of physical changes. Ice and water have the same molecular formula, which is H2O, so that no new substance is formed.
Chemical change known as chemical reactions characterized by several features:
1. discoloration.
2. temperature changes.
3. emergence of sediment.
4. emergence of gas.
In the combustion of gasoline there is a process of chemical change. If we assume gas consisting of octane, gasoline combustion reaction:
8 CO2(g) + 4 H2O(g)">C8H8 (g) + 12 O2 (g) ----> 8 CO2 (g) + 4 H2O (g)
karbondioksida + uap air">gasoline + oxygen ----> carbon dioxide + water vapor
Seen that the new substance is formed of carbon dioxide and water vapor molecules have a different formula with the initial substances and oxygen gas.
More physical changes we know as being a change agent. In the form of the substance changes, no new substance is formed. Although the substance has changed his form but still has a chemical formula of the same molecule. Various kinds of physical changes:
1. Melting: changing the form of a substance from solid to liquid.
2. Yawning: a substance changes from liquid form to gas.
3. Sublime: changes in gas form to the substance of the solid / vice versa.
4. Condense: changes in substance from the gas form into the liquid.
5. Frozen: changes in substance from liquid form to solid.
Change the ice melts into water are examples of physical changes. Ice and water have the same molecular formula, which is H2O, so that no new substance is formed.
Chemical change known as chemical reactions characterized by several features:
1. discoloration.
2. temperature changes.
3. emergence of sediment.
4. emergence of gas.
In the combustion of gasoline there is a process of chemical change. If we assume gas consisting of octane, gasoline combustion reaction:
8 CO2(g) + 4 H2O(g)">C8H8 (g) + 12 O2 (g) ----> 8 CO2 (g) + 4 H2O (g)
karbondioksida + uap air">gasoline + oxygen ----> carbon dioxide + water vapor
Seen that the new substance is formed of carbon dioxide and water vapor molecules have a different formula with the initial substances and oxygen gas.
Jumat, 08 Januari 2010
bahan2 kimia dalam makanan
Seiring dengan perkembangan teknologi pangan,maka pengolahan bahan makanan atau minuman pun makin banyak variasinya.oleh sebab itulah, diperlukan macam-macam bahan,ada yang alamiah dan sintetis guna menunjang pengolahan bahan -bahan makanan ataupun juga minuman biar rasanya tuh lebih pas di lidah orang aja padahal mungkin ada yang pas di lidah ga' pas di tubuh...(eh jadi keterusan neh bahas yang lainya he3x)
Bahan kimia yang di tambahkan di makanan ataupun minuman sebutannya sih zat aditif makanan.berdasar dari asalnya tuh zat aditif makanan(bahan kimia makanan) terbagi menjadi dua loch:
a.Bahan kimia alami(zat aditif alami)
Bahan kimia yang diberikan pada makanan yang berasal alami ,seperti dari hewan (hewani),maupun nabati(dari tumbuh-tumbuhan).
b.Bahan kimia buatan(sintetis)
Bahan kimia yang dicampurkan pada makanan yang berasal dari rekayasa/reaksi senyawa kimia tertentu.
bahan kimia diatas Berdasarkan
Fungsinya tuh terbagi menjadi:
-Bahan pewarna makanan
-Bahan pemanis
-Bahan pengawet
-Bahan penyedap
Langganan:
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