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Chem 1104 Chapter 4 Reactions in Aqueous Solution LECTURE OUTLINE I. Solution Terminology Solution --a *uniform in appearance *2 or more components *transparent separable by physical means Examples: Solute --substance ; usually present in the amount. Solvent --substance the ; usually present in the amount; usually for this class. Example: Identify the solvent and solute in each of the following descriptions of solutions: a) 50mg NaCl and 500mg H 2 O b) 30mL ethanol and 5 mL water II. The Dissolving Process A. Illustrated Solvent: H 2 O Solute: NaCl (ionic) Illustrated: NaCl dissolving in H 2 O B. Predicting Solubility --not all ionic compounds are soluble in water.
Use Solubility Rules : Soluble in Water Insoluble in Water All salts with Group IA ions, NH 4 1+ All salts with NO 3 1-, ClO 3 1-, ClO 4 1-, acetate ion Most salts with SO 4 2- except... BaSO 4 , PbSO 4 , SrSO 4 Salts with Cl 1- , Br 1- and I 1- except... those containing Ag 1+ , Hg 2 2+ , Pb 2+ Salts with F1-^ except... those containing Group IIA and Pb2+ Most salts w/ CO 3 2-, PO 4 3-, C 2 O 4 2-, CrO 4 2-, S2- Most metal hydroxides (OH 1- ) & oxides (O 2- ) Would the following be soluble or insoluble in water? a) Na 2 CO 3 b) PbCl 2 c) LiSO 4 d) CaO III. Electrolytes & Nonelectrolytes -- ability to conduct electricity or not depends on presence of particles and of A. Strong Electrolytes --substance which exists only as when dissolved in water. Are conductors of electricity. Soluble compounds and fit into this category. B. Weak Electrolytes --substance which exists as with a few present. Are conductors of electricity. are in this catagory. C. Nonelectrolytes --substance which exists as when dissolved in water. Are -conductors of electricity due to lack of
AB + CD -----> AD + CB
A. Precipitation Reaction --when a product is formed from mixed aqueous solutions. (Solubility Rules used to predict ppt.) Example: B. Neutralization Reaction --when an reacts with a to yield and a. acid --a substance which produces ( ) when dissolved in water. base --a substance which produces ( ) when dissolved in water. Example:
5. Combustion Reaction --burning of a substance in the presence of ; if substance is -based, it will form and. CxHyOz + O 2 -----> CO 2 + H 2 O + energy Example: **V. Oxidation-Reduction Reactions A. Definition
- In Terms of Oxygen** : oxidation -- of oxygen reduction -- of oxygen oxidizing agent --is itself but is responsible for the other substance reducing agent --is itself but is responsible for the other substance
Fe 2 O 3 (s) + 3 CO(g) ------> 2 Fe(s) + 3 CO 2 (g) 2 Mg(s) + O 2 (g) ------> 2 MgO(s)
2. In Terms of Electrons : " LEO the lion says GER " How is charge affected? 2 Ag1+^ (aq) + Cu(s) ------> 2 Ag(s) + Cu2+^ (aq) B. Determining Oxidation Numbers (p. 119)
- Elements have an oxidation number of since they are neutral. Cu(s) Hg( l )
- Monatomic ions have an oxidation number to their charge. Cu2+(aq) O2-
- Halogens are usually unless combined with oxygen or fluorine. CaCl 2 (aq) ClO1-(aq)
- H is usually unless written as the anion; then it becomes. HClO(aq) CaH 2
- O is usually unless written as a which then has oxidation number. H 2 O(l) H 2 O 2 (aq)
- The algebraic sum of oxidation numbers in a neutral compound must be .
- The algebraic sum of oxidation numbers in a polyatomic ion must be equal to the . Examples: Determine the oxidation numbers for the underlined atoms in the following:
Mg(OH) 2 (aq) + HCl(aq) ---------> +
1. Predicting Products / **Balancing
- Writing Ionic Equation
- Writing Net Ionic Equation** C. Single Displacement Example: AgNO 3 (aq) + Cu(s) --------> + 1. Balance **Equation
- Write Ionic** **Equation
- Write Net** Ionic Equation VII. Solution Concentration A. Molarity --the ratio of per of solution. c molarity = M = Mixing a solution of specific concentration: B. Ion Concentration
If 0.222g CaCl 2 is dissolved in water to make 200mL of solution, what is the ion concentration for that solution? C. Dilution of Solutions --take a certain amount of solution of concentra- tion and add to dilute it. The number of remains unchanged while the amount of changes. M (^) conc V (^) conc = M (^) dil V (^) dil Example: What volume in mL of a 0.75M H 2 SO 4 solution is needed to make 250mL of a 0.50M solution? Describe how you would make it? VIII. Titration --an analytical method for determining of a substance; typically makes use of an reaction. buret of KNOWN concentration of UNKNOWN concentration indicator --dye that changes at various ranges phenolphthalein--colorless in acidic conditions, pink in basic conditions.
