1. Types of Chemical Reactions

2. States  From this point forward, all components of a chemical reaction will need to show the state  There are 4 states 1. Solid 2. Liquid 3. Gaseous 4. Aqueous – Dissolved in water An Aqueous substance will be ionic and is actually the ions separated from each other by water

3. Types of Chemical Reactions  There are only five (5) different types of chemical reactions:  1) Double Replacement  2) Single Replacement  3) Synthesis/Formation  4) Decomposition  5) Combustion

4. Reaction Type 1 – Double Replacement  Occur between two ionic compounds  Does not happen with covalent compounds  Involves an exchange of cations (positive ions)  The cation of one compound trades places with the cation of another compound to form two new compounds

5. Double Replacement - Characteristics  occur in solution when the compounds are in an aqueous state (aq)  reactants are either aqueous to begin with, or solid compounds dissolved in water to form an aqueous solution of ions  in order to drive the reaction, one of the products must be removed from the aqueous solution  this can occur via one of three ways:

6. Double Replacement - Characteristics 1) Formation of a precipitate (an insoluble solid forms in the solution)  i.e.: AgNO 3 (aq) + NaCl (aq)  NaNO 3 (aq) + AgCl (s)  Solid silver chloride is formed as precipitate and comes out of the solution

7. Double Replacement - Characteristics 2) Formation of a gas  i.e.: FeS (aq) + 2HCl (aq)  H 2 S (g) + FeCl 2 (aq)  Hydrogen sulfide gas is formed and comes out of the solution

8. Double Replacement - Characteristics 3) Water is formed when a hydrogen cation unites with a hydroxide anion  i.e.: NaOH (aq) + HCl (aq)  HOH (l) + NaCl (aq)  Water (HOH) is formed and comes out of the solution

9. Determining if a Double Replacement Reaction Occurs & Predicting the States of the Products  1) Formation of a Precipitate  Use a “Solubility Table”  Look at the compounds formed, and use a solubility table to identify if a precipitate is formed  If a precipitate is formed, it will be written as a solid in the products  If no precipitate forms, the reaction will not occur. You will simply have a mixture of ions

10. Determining if a Double Replacement Reaction Occurs & Predicting the States of the Products  2) Formation of a gas  Solubility table is not helpful  More difficult to identify  Use your best judgment, or the info will be given in the question  3) Formation of water  If water is a product, it will be written as a “liquid”, not “aqueous” since it is a pure liquid  Yes, water is technically a covalent compound, however it is still present in double replacement reactions.  Sometimes it is helpful to write H 2 O as HOH symbolizing the joining of a H+ cation and an OH- anion

11. Identifying a Double Replacement Reaction  Double replacement reactions always have two ionic compounds on the REACTANTS side AND on the PRODUCTS side of an equation  *Two compounds react to form two new compounds*  AB + CD  CB + AD  A & C are cations, B & D are anions  A & C switch places

12. Reaction Type # 2 – Single Replacement

13. Single Replacement Reactions: Characteristics:  Atom (s) of a lone element replace the atom (s) of an element in a compound  Metals replace metals (or cations replace cations)  Non-metals replace non-metals (or anions replace anions)

14. Single Replacement Reactions: Characteristics:  Metal Cation Replacement:  For the reaction: A + BC  B + AC  A and B are cations  A “replaces” B in the compound

15. Single Replacement Reactions: Characteristics:  Non-metal Anion Replacement:  For the reaction: D + EF  ED + F  D & F are anions  D “replaces” F in the compound  Non metal replacements usually involve halogens

16. Single Replacement Reactions

17. Restrictions on Single Replacement Reactions  Activity Series:  A characteristic of metals and halogens referring to their reactivity  Determines whether or not a single replacement reaction will occur or not  Metals: on page 155 (table 7-2) there is an activity series of metals arranged in order of decreasing activity  Non-metals (Halogens) : as you move down the group on the periodic table activity decreases

18. Restrictions on Single Replacement Reactions  A single replacement reaction WILL NOT OCCUR if the reactivity of the pure element reactant is less than that of the compound reactant  i.e.: Sn (s) + NaNO 3 (aq)   no reaction b/c tin is less reactive than sodium

19. Restrictions on Single Replacement Reactions  A single replacement reaction WILL OCCUR if the reactivity of the pure element reactant is greater than that of the compound reactant  i.e.: Zn (s) + H 2 SO 4 (aq)  ZnSO 4 (aq) + H 2 (g)  Reaction occurs because the reactivity of zinc is higher than hydrogen

20. Identifying Single Replacement Reactions  Single replacement reactions ALWAYS have 1 lone element and 1 compound on the reactants side and the products side  Reactants will always be:  1 lone element + 1 compound  Products will always be:  1 lone element + 1 compound