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Reaction Notes Part II

Reaction Notes Part II. How to balance a chemical equation. Why do we need to balance a chemical equation?. Sometimes, a written equation DOES NOT have equal number of reactants and products . Example :

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Reaction Notes Part II

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  1. Reaction Notes Part II How to balance a chemical equation

  2. Why do we need to balance a chemical equation? • Sometimes, a written equation DOES NOT have equal number of reactants and products. • Example: • Key Thought: A balanced chemical equation gives scientists information about the relative ratio between the number of reactants and the number of products.

  3. How to “balance” a chemical equation • To balance a chemical equation, chemists use COEFFICIENTS. • Example:

  4. The “Easy” Method of Balancing • The acronym MINOH makes balancing chemical reactions a little easier. TitleExamples • The acronym CHO makes combustion reactions much easier to balance. Title

  5. The Process of Balancing I • Na + Cl2 → NaCl • Step 1: • Step 2: • NOTICE: When the number of products and reactants do not equalthe equation must be unbalanced.

  6. The Process of Balancing II • Na + Cl2 → NaCl • Step 3: Apply the coefficient to the equation • Step 4: Distribute the coefficient to each atom. • Step 5: Check to see if the products and reactants equal

  7. Balancing Example #2 • Fe + O 2 → Fe3O2 • NOTICE: Subscripts indicate how many are present to the LEFT.

  8. Balancing Example #2 • 3Fe + O2 → Fe3O2 • REACTANT SIDE • Fe : 1 x 3= 3 • PRODUCT SIDE • Fe :3 x1 = 3 • NOTICE: Now Fe and O2have the same number of atoms when they react to form Fe3O2.

  9. Balancing Example #3 • C4H8 + O2 → CO2+ H2O • REACTANT SIDE • PRODUCT SIDE • NOTICE: On the PRODUCT side, O is present in BOTH products.

  10. Balancing Example #3 • C4H8 + 6O2 → 4CO2+ 4H2O • REACTANT SIDE • PRODUCT SIDE • NOTICE:This equation satisfies the Law of Conservation of Mass by using coefficients.

  11. Balancing Example #4 • Ag2S+ KCN→ KAg(CN)2+ K2S • REACTANT SIDE • PRODUCT SIDE • K : 1 + 2 • NOTICE:All atoms have the same numbers in both Products and Reactants.

  12. Balancing Example #5 • Hg(OH)2 + H3PO4→ Hg3(PO4)2+ HOH • REACTANT SIDE • Hg: 1 • OH: 2 • H: 3 • PO4: 1 • PRODUCT SIDE • NOTICE: All atoms have the same numbers in both Products and Reactants.

  13. Balancing Example #6 • I2 + HNO3 → HIO3 + NO2 + H2 • I: • H: • NO3: • IO3: • H: • N: • O: • NOTICE: All atoms have the same numbers in both Products and Reactants.

  14. Balancing Example #7 • C4H10 + Cl2 + O2→ CO2 + CCl4 + H2O • C: • H: • Cl: • O: • C: • H: • Cl: • O: • NOTICE: All atoms have the same numbers in both Products and Reactants.

  15. In-Class/Homework Assignment • Homework: • Worksheet: Balancing Chemical Equations, 1-25

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