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)  Cu 2 S(s) –2Fe(s) + 3S(s)  Fe 2 S 3 (s) –K(s) + Cl 2 (g)  ? ions are: K +1 and Cl -1 therefore: K(s) + Cl 2 (g)  KCl(s) balanced: 2K(s) + Cl 2 (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) + O 2 (g) –Zn(ClO 3 ) 2  ZnCl 2 + 3O 2 –H 2 O(l) → ? H 2 O(l) → H 2 (g) + O 2 (g) 2H 2 O(l) → 2H 2 (g) + O 2 (g) 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)  ZnCl 2 (aq) + H 2 (g)

–Ni + AgNO 3  ? nickel replaces the metallic ion Ag +1. silver becomes free silver and the nickel becomes the nickel(II) ion (Ni +2 ) NO 3 is 1- Ni + AgNO 3  Ag + Ni(NO 3 ) 2 –balance the equation: –Ni + 2AgNO 3  2Ag + Ni(NO 3 )

Al + Fe 2 O 3  ? –O is 2- and therefore Fe was 3+ –aluminum will replace iron(III) –iron(III) becomes Fe and aluminum metal becomes Al 3+ –Al + Fe 2 O 3  Fe + Al 2 O 3 –2Al + Fe 2 O 3  2Fe + Al 2 O 3 Cl 2 +2 NaI  ? –Cl 2 +2NaI  2 NaCl + I 2

Double Replacement Reactions an exchange of positive ions between two chemicals general form is AX + BY  BX + AY CuSO 4 + Na 2 CO 3  Na 2 SO 4 + CuCO 3

NaOH + CuSO 4  ? The Na + and Cu 2+ switch places. Na + combines with SO 4 2- to form Na 2 SO 4. Cu 2+ combines with OH - to form Cu(OH) 2 NaOH + CuSO 4  Na 2 SO 4 + Cu(OH) 2 2NaOH + CuSO 4  Na 2 SO 4 + Cu(OH) 2

Na 2 CO 3 + HCl  ? Na +1 combines with Cl -1 to form NaCl H + combines with CO 3 2- to form H 2 CO 3 Na 2 CO 3 + 2HCl  2NaCl + H 2 CO 3

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

CH 4 + O 2  ? CH 4 + O 2  CO 2 + H 2 O CH 4 + 2O 2  CO 2 + 2H 2 O

Practice Classify each of the following as to type: H 2 + Cl 2  2HCl –combination Ca + 2H 2 O  Ca(OH) 2 + H 2 –single replacement

Practice 2CO + O 2  2CO 2 –combination and combustion 2KClO 3  2KCl + 3O 2 –decomposition

Practice FeS + 2HCl  FeCl 2 + H 2 S –double replacement Zn + HCl  ? –single replacement –Zn + 2HCl  ZnCl 2 + H 2