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Chemical Equations & Balancing

Chemical Equations & Balancing. What is a chemical equation?. A standard way to describe a chemical reaction. This means that scientists worldwide use this system. Show the number and combinations of elements & compounds involved in the reaction. Chemical Equations ….

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Chemical Equations & Balancing

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  1. Chemical Equations & Balancing

  2. What is a chemical equation? • A standard way to describe a chemical reaction. • This means that scientists worldwide use this system. • Show the number and combinations of elements & compounds involved in the reaction.

  3. Chemical Equations … • 2 Parts to a chemical equation: • Reactants = original substance(s) (substances before any reaction occurs) • Products = created during the reaction (ending substances) http://scoutmaster.typepad.com/photos/uncategorized/2007/03/18/vinegar.jpg http://www.agoosa.com/images/baking-soda.jpg NaCH3COO NaHCO3 H2O CH3COOH CO2 http://www.achilles-online.com/catalog/pics/Sodium_Acetate__Anhydrous.jpg http://www.scienceclarified.com/images/uesc_02_img0110.jpg http://keetsa.com/blog/wp-content/uploads/2008/03/water-conservation.jpg

  4. General Chemical Equations: Reactant + Reactant  Product + Product • Not all reactions have 2 reactants and 2 products (could be one or more for each). Reactants written before the arrow. Products written after the arrow. Arrow represents chemical reaction.

  5. For example: Label the reactants and products in this equation. • How do you say this? Sodium and chlorine react to form sodium chloride. 2Na + Cl2 2NaCl Reactants Product In chemical reactions, the number and kinds of elements are always the same!

  6. Chemical Equations also show Conservation of Mass: • There must be the same amount of each element in the reactants as in the products (although the element could be part of different compounds). http://media.photobucket.com/image/balance%20scales/nbest221/scales.jpg

  7. Coefficients: • Used to show conservation of mass in a chemical equation. • Whole number put in front of a reactant or product to show a balanced chemical equation. 2Na + Cl2 2NaCl • Multiplies the element(s) found in that specific reactant or product.

  8. Balancing Chemical Equations: • Write each reactant and product. (Remember how ions form chemical bonds.) • Add coefficients to change the number of atoms within a substance. • Never change the subscripts!

  9. 2 H2O2 2 H2O + O2 H2O2 H2O + O2 • Reactants? • H in reactants? • H in products? • O in reactants? • O in products? • Mass conserved? Why? • Without coefficients – conservation? 2 = 4 = H = 4 = 2 2 = 4 = O = 3 = 4 YES! H = 2 X 2 = 4 O = 2 + 2 = 4 When Reactants = Products then mass is conserved! Does NOT show Conservation of Mass because Reactants do NOT equal Products. O = 2 X 2 = 4 H = 2 X 2 = 4

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