Unformatted text preview: Chemical Reactions and Equations Unit 5/ Ch 11 The Equation Reactants Products. Analogy to the English sentence: Used to describe what is occurring in the reaction. Additional symbols are used as adjectives in the equation. Symbols + :used to separate reactants and/or products. :“yields” separates reactants and products. :reversible reaction at equilibrium. (s) or (cr) :solid state of matter (crystalline). (l) :liquid state of matter. Symbols (g) or (vp) :gaseous or vapor state of matter. (aq) :(aqueous) dissolved in H2O, a homogeneous solution. Two liquids (aq) combined and one product formed is a precipitate or solid (ppt). As a product gas is being released. Diatomic Molecules H2 N2 F2 O2 Cl2 I2 Br2 71st Rule The Process
When balancing an equation the number of atoms of each element on each side of the yield sign must be equal. This ensures the “Law of Conservation of Matter” is obeyed. Balancing Equations
• The Process List the elements on both sides of the yield sign. List the number of atoms for each element If they do not match determine the common multiple that will make them equal. Whatever you multiply by becomes the coefficient in front of the substance.
distribute the subscript through the ( ). 3. 4. 1. 2. 3. Change any other element that is changed. Continue the process until every element is equal. If any blank is not filled, place the number one, even though it is understood. Chemical Reaction Types
• • • Combination or Synthesis: 2.
• • • • Decomposition: Element + Element Compound There is only one product formed. 2Al + N2 2AlN Compound Element + Element There can only be one reactant. Cu(CO3) CuO + CO2 2Fe2O3 4Fe + 3O2 1.
• Single Replacement or Single Displacement:
• • • Element + Compound Element + Compound Metals only replace metals, and nonmetals only replace nonmetals. Cu + 2Ag(NO3) Cu(NO3) + 2Ag 2KCl + Br2 2KBr + Cl2 4. Double Replacement or Double Displacement:
• • • Compound + Compound Compound + Compound Combine the outside two elements, and combine the inside two elements (“foil method”). KCl + Ag(NO3) K(NO3) + AgCl 1. Combustion • Organic Compound + Oxygen Carbon Dioxide + Water • When balancing a combustion reaction assume that the coefficient in front of the organic compound is one. Balance the carbon, hydrogen, then oxygen. If you come out with a fraction multiply everything by two. • Examples:
• • C 2H 6 C5H12 ...
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- Fall '08
- Reaction, Sign, 2AlN Compound Element, Compound + Compound