decomposition,+slevey+2008.

//decomposition.//
//definition:// decomposition is when a substance is broken down into two or more simpler substances. this is one of the easier reactions, along with synthesis.

//generic form of equation:// this reaction can be represented by this equation: AB  à A + B.

//an example of decomposition:// water **decomposes to produce** dihydrogen and dioxide. (the **decomposes** **to produce** in this equation is the same as the '  à ' in a chemical equation.)

//changing the sentence into a chemical equation:// in order to change this sentence into a chemical equation or formula, you have to know each element's atomic symbol. hydrogen is represented by H, and oxygen is represented by O. after you have the atomic symbols, look at the number prefixes before eact element. __di__hydrogen and __di__oxide. //di// means two (these number prefixes will turn into subscripts for the elements in the equation). so, the final chemical equation will turn out like this: H2O  à H 2 + O2

//so how do we balance this new chemical equation?:// in order to balance an equation, there needs to be an equal amount of each element on either side of the equation. so, to make life easier, we'll do a couple steps to figure this out. 1. copy the equation down. H2O  à H 2 + O2

2. underneath the equation, make a column of each atomic symbol. on either side, fill in how many atoms there are of each element. H2O  à H 2 + O2 2 H 2 1 O 2

3. see how there are an even amount of hydrogens on either side, but there are twice as many oxygens on the reactants side than on the product side? this can easily be fixed. we're going to add a //coefficient// to one of the atomic symbols. 2H2O  à H 2 + O2  notice how there was a 2 placed before the water on the product side. this means that you take the coefficient and you multiply it by the amount of atoms of that element (**remember to never change the subscript, just the coefficient**!). so now, there are four hydrogens on the product side. we can now update our column to look like this: 2H2O  à H 2 + O2 4 H 2 2 O 2 okay. so now there are twice as many hydrogens on the product side than on the reactants side, but there are an equal amount of oxygens on either side. so, we'll add another coefficient to the hydrogen on the reactants side. H2O  à 2H 2 + O2 4 H 4 2 O 2 there, now the equation is balanced!



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