Question

30 chemical equations worded: chemical formula; and type of reaction ( combination, decomposition, displacement, double displacement?)

Answer 1

The vast number of chemical reactions can be classified in any number of ways. Under one scheme they can be categorized either as oxidation-reduction (electron transfer) reactions or non-oxidation-reduction reactions. Another completely different but common classification scheme recognizes four major reaction types: 
(1)  combination or synthesis reactions 
(2)  decomposition reactions 
(3)  substitution or single replacement reactions 
(4)  metathesis or double displacement reactions
The Four Major Types of  Reactions      Name                                           General Reaction Pattern 
Combination or synthesis                                 A  +  B ----> AB
Decomposition                                                      AB ---->  A  +  B
Substitution or Single Replacement            A  +  BC ---->  B  +  AC
Metathesis or Double Displacement        AB  +  CD ---->  AD  +  CB
Combination or Synthesis Reactions   Two or more reactants unite to form a single product.

                                     S   +   O2 --------->  SO2 
                               sulphur    oxygen            sulphur dioxide

                                  2 S      +    3 O2 --------->  2 SO3 
                                sulphur            oxygen                 sulphur trioxide

                                2 Fe   +   O2  --------->  2 FeO 
                                iron        oxygen                    iron (II)  oxide 
  
 


Decomposition Reactions   A single reactant is decomposed or broken down into two or more 
                                              products.

                                       CaCO3   ---------->    CaO     +      CO2 
                                calcium carbonate                calcium oxide     carbon dioxide

                                                     2 H2O ----------->  2 H2    +     O2 
                                                         water                           hydrogen        oxygen

                                                 2 KClO3 ----------->  2 KCl   +     3 O2 
                                           potassium chlorate          potassium chloride   oxygen


Substitution or Single Replacement Reactions  A single free element replaces or is substituted for one of the elements in a compound.  The free element is more reactive than the one its replaces.

                          Zn    +     2 HCl   ---------->  H2    +  ZnCl2 
                                  zinc      hydrochloric acid             hydrogen    zinc chloride

                       Cu   +   2 AgNO3  ----------->  2 Ag    +    Cu(NO3)2 
                   copper        silver nitrate                             silver          copper (II) nitrate

                               H2    +   2 AgNO3 ----------->  2 Ag   +   2 HNO3 
                           hydrogen     silver nitrate                            silver           nitric acid

                                  2 Na   +  2 H2O  ----------->  2 NaOH    +     H2 
                                 sodium          water                          sodium hydroxide     hydrogen


Metathesis or Double Displacement Reactions  This reaction type can be viewed as an "exchange of partners."  For ionic compounds, the positive ion in the first compound combines with the negative ion in the second compound, and the positive ion in the second compound combines with the negative ion in the first compound.

                       HCl    +     NaOH  ----------->  NaCl   +  HOH 
                  hydrochloric        sodium                              sodium         water 
                              acid               hydroxide                           chloride

                          BaCl2   +   2 AgNO3 ---------->  2 AgCl    +   Ba(NO3)2 
                            barium                  silver                                    silver                barium 
                            chloride                nitrate                                 chloride              nitrate 
                                                                                                    (precipitate)

                      CaCO3   +   2 HCl   ----------->  CaCl2   +  H2CO3 
                              calcium         hydrochloric                        calcium          carbonic 
                            carbonate