Types of Chemical Reactions

Watch These Reactions!

Combination Reactions• a chemical change in which two or more

substances react to form a single new substance

• the general form is A + X AX– 2Cu(s) + S(s) Cu2S(s)– 2Fe(s) + 3S(s) Fe2S3(s)– K(s) + Cl2(g) ?

• ions are: K+1 and Cl-1

• therefore: K(s) + Cl2(g) KCl(s)• balanced: 2K(s) + Cl2(g) 2KCl(s)

Decomposition Reactions• a chemical change in which a single

compound breaks down into two or more simple products.

• the general form is AX A + X– 2HgO(s) → 2Hg(l) + O2(g)– Zn(ClO3)2 ZnCl2 + 3O2

– H2O(l) → ?• H2O(l) → H2(g) + O2(g)• 2H2O(l) → 2H2(g) + O2(g)

electricity

electricity

electricity

Single Replacement Reactions• a chemical change in which one element

replaces a second element in a compound– metal will replace a metal, or a

nonmetal will replace a nonmetal – general form is A + BX AX + B

– Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g)

– Ni + AgNO3 ?• nickel replaces the metallic ion Ag+1.• silver becomes free silver and the

nickel becomes the nickel(II) ion (Ni+2)• NO3 is 1-

• Ni + AgNO3 Ag + Ni(NO3)2

–balance the equation:–Ni + 2AgNO3 2Ag + Ni(NO3)

• Al + Fe2O3 ?– O is 2- and therefore Fe was 3+

– aluminum will replace iron(III)– iron(III) becomes Fe and aluminum metal

becomes Al3+

– Al + Fe2O3 Fe + Al2O3

– 2Al + Fe2O3 2Fe + Al2O3

• Cl2 +2 NaI ?– Cl2 +2NaI 2 NaCl + I2

Double Replacement Reactions

• an exchange of positive ions between two chemicals

• general form is AX + BY BX + AY• CuSO4 + Na2CO3 Na2SO4 + CuCO3

• NaOH + CuSO4 ?• The Na+ and Cu2+ switch places.• Na+ combines with SO4

2- to form Na2SO4.

• Cu2+ combines with OH- to form Cu(OH)2

• NaOH + CuSO4 Na2SO4 + Cu(OH)2

• 2NaOH + CuSO4 Na2SO4 + Cu(OH)2

• Na2CO3 + HCl ?• Na+1 combines with Cl-1 to form

NaCl• H+ combines with CO3

2- to form H2CO3

• Na2CO3 + 2HCl 2NaCl + H2CO3

Combustion Reaction• a type of combination reaction

where a substance reacts with oxygen

• often the burning of a fuel that produces carbon dioxide, water, light, and heat

• CH4 + O2 ?• CH4 + O2 CO2 + H2O• CH4 + 2O2 CO2 + 2H2O

Practice• Classify each of the following as to type:

• H2 + Cl2 2HCl– combination

• Ca + 2H2O Ca(OH)2 + H2

– single replacement

Practice• 2CO + O2 2CO2

– combination and combustion

• 2KClO3 2KCl + 3O2

– decomposition

Practice• FeS + 2HCl FeCl2 + H2S

– double replacement

• Zn + HCl ?– single replacement– Zn + 2HCl ZnCl2 + H2