AP Chemistry - Common Reactions That You Should Know
1.    A metal and oxygen gas will combine to make a metal oxide.

       eg.  4 Fe  + 3 O2  -----> 2 Fe2O3               eg.   4 Na  +  O2  ----->  2 Na2O

i)  use the periodic table to predict the most likely valence of a transisiton metal.
ii)  metals are always elemental , O2 is always diatomic.
 

2.   A metal in acid will produce a metallic salt and hydrogen gas.  A salt is a positive metal ion and a negative ion ending in "ide", "ate" or "ite".

eg.    2 Na   +  2 HCl   ---->  2 NaCl   +  H2(g)

Na displaces H from the moelcules because Na is more reactive.

eg.    Pb +  H2SO4   -------->   PbSO4   +  H2(g)
 

Exception - Copper and nitric acid do not perform this reaction.

           Cu  +    HNO3 ---> Cu(NO3)2   +   H2O   +   NO2(g)
 

3.  Metals in water form metal hydroxides and hydrogen gas.

eg.      2 Na  +  2 H2O   ----->  2 NaOH  + H2(g)
 

4.  Metal oxides in water form metal hydroxides.

eg.      K2O    +   H2O     -----> 2 KOH

eg.    Fe2O3   +    H2O     ------->  2 Fe(OH)3
 

5.  Peroxides decompose to metallic oxides and oxygen gas

     2 Na2O2   -------->   2 Na2O  +  O2

    2 H2O2   -------->   2 H2O  +  O2
 

6.   Non-metallic elements combine with oxygen to make non-metallic oxides.

           S   +   O2  ---->  SO2

           C    +    O2  ------>   CO2
 

7.   Non-metallic oxides and water combine to form acids.

                SO2     +     H2O   ----->  H2SO3

                NO2    +   H2O   -----> HNO  +  HNO
 

8.    A metal and a compound may react in a single displacement reaction if the metal is more reactive than the metal in the compound.  See the activity series above for more information.

      2  Al(s)    +   6 HCl    ------->   2 AlCl3   +  3 H2(g)

      Cu(s)    +    2 AgNO3   ---->  2 Ag(s)   +  Cu(NO3)2

      Ag(s)   +     Cu(NO3)2  ----->  No reaction
 

9.    An acid and a base will neutralize each other to create water and a salt.

eg.    HCl    +    NaOH    ----->   H2O    +   NaCl

eg.        2  H3PO4    +  3 Mg(OH)2    ------->   6 H2O    +    Mg3(PO4)2
 

10.    Chlorates  and perchlorates decompose on heating to give oxygen and a salt.

         2 KClO3   ------heat------->   2 KCl   +  3 O2

         KClO4    ---------heat------>    KCl   +  2 O2


Go to the Next Stoichiometry Section on Stoichiometry