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balancing-equations

# balancing-equations - How molecules are symbolized Cl2 2Cl...

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How molecules are symbolized Cl 2 2Cl 2Cl 2 Molecules may also have brackets to indicate numbers of atoms. E.g. Ca(OH) 2 O H O H Ca Notice that the OH is a group The 2 refers to both H and O How many of each atom are in the following? a) NaOH b) Ca(OH) 2 c) 3Ca(OH) 2 Na = 1, O = 1, H = 1 Ca = 1, O = 2, H = 2 Ca = 3, O = 6, H = 6
Balancing equations: MgO The law of conservation of mass states that matter can neither be created or destroyed Thus, atoms are neither created or destroyed, only rearranged in a chemical reaction Thus, the number of a particular atom is the same on both sides of a chemical equation Example: Magnesium + Oxygen (from lab) Mg + O 2 MgO O Mg O + Mg O However, this is not balanced Left: Mg = 1, O = 2 Right: Mg = 1, O = 1

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Balance equations by “inspection” Hints: start with elements that occur in one compound on each side. Treat polyatomic ions that repeat as if they were a single entity. 5 2 3 3.5 2 7 4 6 2 2 2 2 6 3 C 2 H 6 + O 2 CO 2 + H 2 O a) P 4 + O 2 P 4 O 10 b) Li + H 2 O H 2 + LiOH c) Bi(NO 3 ) 3 +
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