Chem: Chemical vs Physical changes

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  1. Chemical change
    substance changes into a new and different substance
  2. Physical change
    the substance undergoing the change remains the same (melting of ice)
  3. How can chem rxn be expresses?
    by chem equation
  4. Reactants
    substances that react with each other, left side of equation
  5. Products
    right side of equation
  6. Law of conversation of mass
    Matter is neither created nor destroyed => same number of atoms should be on each side
  7. Main categories of rxn
    • 1) Synthesis
    • 2) single replacement
    • 3) double displacement
    • 4) decomposition
  8. How do we measure a quantity of a substance?
    by moles
  9. mole
    is equal to 6,02 x 10^23 particles
  10. Synthesis rxn
    • also called combination rxn
    • two or more reactants combine to form a new product¬†
    • 2 H2 + O2 => 2H2O

    2 moles of H reacts with 1 mole of O
  11. Single replacement reaction
    element reacting with a compound, and replaces an element in the compound

    Cl2 + 2 NaBr => 2 NaCl + Br2
  12. Double displacement rxn
    • involve two ionic compounds
    • positive ion or metal switch position
    • The common type is an acid base rxn (neutralization rxn)¬†b/c the end products arw neither acidic nor basic : Salt + water
    • F.E
    • NaOH + HCl => NaCl + H2O
    • Base + Acid => Salt + Water
  13. Acid
    • donated H+ in an aqueous solution
    • OR
    • H+ combines with water to form hydronium H3O+ => hydronium ion produced by acid in water
  14. Base
    Donates OH- in aqueous solution
  15. pH scale
    identify the strength of an acid or base depending on a concentration of hydrogen or hydroxide ions
  16. Indicator
    a substance that changes color in an acid or base
  17. Examples of indicators
    • Litmus = red in Acid, Blue in Base
    • Phenolphthalein = purple/red in a Base
    • Bromthymol blue = Yellow in acid
  18. Decomposition rxn
    • One reactant is broken down into two or more simpler products. Often heat is used
    • H2CO3 => H2O + CO2
    • Heated carbonic acid => water + carbon dioxide
Card Set:
Chem: Chemical vs Physical changes
2013-09-16 03:11:32

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