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Chemical Equation


A chemical change can be represented by a chemical equation with chemical symbols. The symbols for the reactants are placed on the left hand side of the equation (before the arrow) and the symbols for the products are placed on the right hand side (after the arrow). The equation has to be balanced in terms of the number of moles of the reactant elements and the number of moles of the product elements.
   
In the example of the burning of hydrogen, the chemical equation is

2 H2 + O2 2 H2O
for the word equation
hydrogen + oxygen water
     
The number that is placed in front of the symbol for the element or compound is known as the coefficient. The coefficient denotes the number of of moles. In the equation above, two moles of hydrogen react with one mole of oxygen to produce two moles of water. The subscript that is placed after the element symbol shows the number of atoms for that element.



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Persamaan Kimia
         
Suatu perubahan kimia boleh diwakili oleh persamaan kimia dengan simbol-simbol kimia. Simbol-simbol kimia reaktan ditulis pada bahagian kiri persamaan (sebelum anak panah) dan simbol-simbol hasil / produk kimia ditulis di bahagian kanan (selepas anak panah). Persamaan kimia mesti diseimbangkan. Bilangan mol unsur reaktan mesti menyimbangi bilangan mol unsur reaktan produk.
   
Dalam contoh pembakaran hidrogen, persamaan kimia adalah

2 H2 + O2 2 H2O
untuk persamaan perkataan
hidrogen + oksigen air
   
Nombor yang ditulis sebelum simbol unsur atau sebatian dikenali sebagai pekali / koefisyen. Pekali / Koefisyen menunjukkan bilangan mol. Dalam persamaan di atas, dua mol hidrogen bertindak balas dengan satu mol oksigen untuk menghasilkan dua mol air. Subskrip yang ditulis selepas simbol unsur menunjukkan bilangan atom bagi unsur tersebut.


 
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