Types of Chemical Reactions

Steps to Writing Reactions Some steps for doing reactions 1.Identify the type of reaction 2.Predict the product(s) using the type of reaction as a model 3.Balance it Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2 memorize these

Watch These Reactions!

Combination ( or Synthesis) 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)

Practice Predict the products. Write the following synthesis reaction equations. Sodium metal reacts with chlorine gas Na + Cl 2  NaCl Solid Magnesium reacts with fluorine gas Mg + F 2  MgF 2 Aluminum metal reacts with fluorine gas Al + F 2  AlF 3 Now balance….

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

Practice Predict the products. Then, write and balance the following decomposition reaction equations: Solid Lead (IV) oxide decomposes –Pb is 4+ and O is 2- therefore… PbO 2  Pb + O 2 Aluminum nitride decomposes –Al is 3+ and N is 3- therefore… AlN  Al + N 2

May want to stop here

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  B + AX –zinc metal reacts with aqueous hydrochloric acid –Zn (s) + 2HCl (aq)  ZnCl 2 (aq) + H 2 (g)

–Ni + AgNO 3  ? both Ni and Ag are positive ions see the activity series table to see which is the most reactive –since nickel is… silver becomes free silver and the nickel becomes the nickel(II) ion (Ni +2 ) and will replace the silver NO 3 is 1- Ni + AgNO 3  Ag + Ni(NO 3 ) 2 –balance the equation: –Ni + 2AgNO 3  2Ag + Ni(NO 3 ) 2

aluminum metal reacts with aqueous copper (II) nitrate –Al is a metal / Cu is 2+ and NO 3 is 1- –Al (s) + Cu(NO 3 ) 2(aq)  ? –Al is higher on the reactivity table and will replace Cu –the new product is a result of the new Al 3+ and NO 3 1- ions bonding –Al (s) + Cu(NO 3 ) 2(aq)  Cu (s) + Al(NO 3 ) 3(s) –2Al (s) + 3Cu(NO 3 ) 2(aq)  3Cu (s) + 2Al(NO 3 ) 3(s)

Al + Fe 2 O 3  ? –O is 2- and therefore Fe was 3+ –aluminum will replace iron(III) –iron(III) becomes simply 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 Another one, but not as good as the last one

Double Replacement Reactions an exchange of positive ions between two chemicals –a reaction will occur if any of the new products are any of the following: a gas water a precipitate (see solubility table/cheat sheet) general form is AX + BY  BX + AY CuSO 4 + Na 2 CO 3  Na 2 SO 4 + CuCO 3

NaOH + CuSO 4  ? –look at the table to see if either new product will form a precipitate– if so, this indicates a reaction will take place –yes, copper (Cu) and hydroxide (OH) will form a precipitate according to the table therefore, the Na + and Cu 2+ will 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

Assume the following double replacement reaction will take place: –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 –word equation?

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 Which type of reaction are the following? H 2 + Cl 2  2HCl –combination Ca + 2H 2 O  Ca(OH) 2 + H 2 –single replacement

Practice 2CO + O 2  2CO 2 –combination 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