Reactions in General

1. proper reactant formulas

2. proper product formulas

3. phases on all reactants and products

4. balance the reaction

names and/or formulas of R. & P.

ionic vs covalent compounds

element molecular forms:  X2, P4, S8

element phases

 

Non-aqueous reactions

pure materials, no net ionic equations

Aqueous Reactions

Net ionic equations apply

1. combustion (a common redox process)

    example = cellular respiration p 145

    CH4(g)  +   O2(g)  à   CO2(g)   +   2H2O(liq.)

  • + O2(g)
  • makes separate oxides
  • CxHy and CxHyOz make predictable products
  • balance O2 last
  • metals (charge specified as needed)
  • nonmetals (products and phases typically specified)

5. precipitation reactions (type of exchange or double displacement)

    example =  carbon cycle (limestone, etc.)

    CaCl2(aq)   +    (NH4)2CO3(aq)  à   CaCO3(s)  + 2NH4Cl(aq)

    Ca+2(aq)   +    CO3-2(aq)  à   CaCO3(s)  (net ionic)

  • page 120 - 121 predicts those ion combinations that form ppts
  • see examples on pp 121 – 122
  • balancing tip: count intact polyatomic ions

 

2. metals + nonmetals (also called combination, a redox process)

    example = formation of ionic solids from the elements p 211

     Na(s)   +   1/2Cl2(g)  à  NaCl(s)

  • TWO reactants make ONE product
  • nonmetal reactant (s, liq. g) specified by you
  • metals (charge specified in product as needed)
  • product phase assumes pure ionic compound

6. acid and base (type of exchange reaction)

      2HNO3(aq)  +   Ca(OH)2(aq)  à  2H2O(liq)   +   Ca(NO3)2(aq)

      H+(aq)  +  OH-(aq)  à H2O(liq)   (net ionic)

  • str. acid (p 118) + str. base -->  H2O(liq.) + leftovers
  • balancing tip: look for each H+ + OH -  =  H2O

3. two nonmetals (combination, a redox process)

    example = nitrogen fixation p 834

    N2(g)  +   3H2(g)  à  2NH3(g)

  • TWO reactants make ONE product
  • nonmetal reactant (s, liq. g) specified by you
  • product name and phase will be given

7. acid + carbonate

    example = lungs (the tailpipe of cellular respiration)

    2HCl(aq)   +    CaCO3(s)  à   CO2(g)  + H2O(liq)  +   CaCl2(aq)

    2H+(aq)  +  CaCO3(s)  à CO2(g)  + H2O(liq)  +  Ca+2(aq) (net ionic)

  • Acid (p 118) + carbonate --> CO2(g)  +  H2O(liq.) + leftovers
  • balancing tip: look for each 2H+  +   CO3-2 --> CO2 + H2O

 

4. decomposition

     CaCO3(s)  à   CaO(s)   +   CO2(g)

  • ONE reactant makes TWO different products
  • metal carbonates predictable, make oxides and CO2(g)
  • other decomposition products will be described

8. acid + metal (type of displacement reaction, also a redox process)

     3HBr(aq)  +   Al(s)   à  AlBr3(aq)  +  3/2H2(g)

     3H+(aq)  +   Al(s)   à  Al+3(aq)  +  3/2H2(g)   (net ionic)

  • Acid (p 118) + metal*  -->  H2(g)  +   metal ion  + leftovers
  • metal ion charge will be specified if needed

            * for metals that do this, see p 132