Chapter 5 Reactions in Aqueous Solutions Titrations Kick Acid!!! 1 I. Properties of Aqueous Solutions A) Electrolytes and Non-Electrolytes B) Predicting Solubility* II. Reactions of Ionic Compounds in Solution* III. Acid-Base Reactions IV. Oxidation-Reduction Reactions A) Recognition (Oxidation States) B) Balancing REDOX Reactions V. Titrations http://chemskills.com/sites/default/files/titration.jpg, https://i.ytimg.com/vi/zuexl9462rq/hqdefault.jpg, http://49.media.tumblr.com/065da7724d1cf2a09ffc792c210987bc/tumblr_n0hqmamxqd1tozyi0o1_500.gif, http://49.media.tumblr.com/c8e0ef8739a3a87164fee0128e221ad8/tumblr_nemaa55joh1sn5m44o1_400.gif, https://upload.wikimedia.org/wikipedia/commons/f/ff/color_of_various_ni%28ii%29_complexes_in_aqueous_solution.jpg, http://cdn.c.photoshelter.com/imgget/i0000bdl2gj6iak8/s/600/600/acid-base-reaction-baking-soda-vinegar.jpg
I. Properties of Aqueous Solutions 2 What is an aqueous solution? 1. What is a solution? - a homogeneous mixture of two or more substances - solute(s) and solvent e.g. NiCl 2 in H 2 O 2. What does aqueous mean? - solute dissolves in water Three Possibilities (aq) substance dissolves (s) substance does not dissolve, solid (l) substance does not dissolve - either solvent or insoluble liquid What Happens When Compounds Dissolve in Water? m3.static.flickr.com/2392/1507307061_ca48a57f17.jpg?v=0
A. Soluble Compounds: Electrolytes and non-electrolytes 3 1. Electrolytes - Compounds that dissolve to produce ions in solution a) strong b) weak 2. Non-Electrolytes - Compounds that dissolve but do not produce ions 1. Electrolytes Strong Electrolytes for every molecule or formula unit that dissolves we get at least 2 ions Which Compounds? - soluble ionic compounds and all strong acids and bases Weak Electrolytes for every molecule or formula unit that dissolves only a small fraction produce ions Which Compounds? - weak acids and weak bases
Soluble Ionic Dissociate Soluble - at least 0.1 moles of the compound dissolves per liter of solution 4 Slightly Soluble - 0.01 but < 0.1 moles of the cmpd dissolves per liter of solution Insoluble Ionic - less than 0.01 moles of the cmpd dissolves per liter of solution
Acids - produce H 3 O + when dissolved in water - H first in the formula or after COO (acidic H s)* NH 3 HC 2 H 3 O 2 H 3 PO 4 CH 3 COOH - Chem 180 acids are soluble in water Strong Acid Acid dissolves and each molecule ionizes to produce at least one H 3 O + HCl, HBr, HI, HNO 3, H 2 SO 4, HClO 4 Weak Acid Acid dissolves but only a small fraction ionizes to form H 3 O + *(weak electrolyte)
Bases - react with H 3 O + and produce OH - when dissolved in water (directly or indirectly) - soluble ionic cmpd with OH -, neutral molecular cmpd with N, soluble ionic cmpd w/out Cl -, Br -, I -, etc.* direct 6 indirect Strong Base Each molecule or formula unit dissolves and produces at least 1 OH - Common Strong Bases LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH) 2, Sr(OH) 2, Ba(OH) 2
Weak Base only a small fraction of each base produces at OH - (weak electrolyte) 7 Is C 2 H 5 OH a strong base or even a base?
Acid and Base Behavior of Ions - almost any ion with a negative charge can act as a base in solution - some cations can act as acids 8 Cations
Anions 9 Label the following compounds as acidic basic or neither. - Identify the principle species in solution NH 4 Cl(aq) C 12 H 22 O 11 (aq) KCN(aq) LiClO 4 (aq)
Solubility Rules for Common Ionic Compounds SOLUBLE COMPOUNDS group 1 cations + any anion soluble ammonium ion + any anion soluble Any cation + nitrate, perchlorate, soluble or acetate ions MOSTLY SOLUBLE COMPOUNDS Any cation + chloride, bromide, or iodide ions (except lead(ii), silver, mercury(i) insoluble) soluble Any cation + sulfate ions soluble (except strontium, calcium, barium, lead(ii), mercury(i) insoluble) INSOLUBLE COMPOUNDS Any cation + hydroxide ions insoluble (except group I, ammonium, calcium*, barium*, strontium* soluble) Any cation + sulfide ions (except group I, ammonium, group II* soluble) Any cation + carbonate or phosphate ions (except group I, ammonium soluble) Insoluble Insoluble * - slightly soluble
B. Predicting Solubility of Ionic Compounds 10 Example Problem If I add enough water to the following chemicals to make 1 liter of solution, which will have the largest [Cl - ] when they are made? a.) 2.0 mole NaCl b.) 2.0 mole CaCl 2 c.) 3.0 mole PbCl 2
II. Reactions of Ionic Compounds in Solution 11 A. Metathesis or double displacement AX + BY AY + BX
3 Types of Equations Can Describe Reaction 1. Complete Equation (complete chemical formulas) 2. Total Ionic Equation (what exist as soln) 3. Net Ionic Equation (ions that do something) 12 1. Complete Equation 2. Total Ionic Equation 3. Net Ionic Equation
Example Problem Another Way (Identify the principle species in solution) 13 Reactants Net Ionic Equation
III. Acid-Base Reactions 14 Acid-Base Reactions That Always Occur 1. Strong Acid + Strong Base Reaction Will Occur 2. Weak Acid + Strong Base Reaction Will Occur 3. Strong Acid + Weak Base Reaction Will Occur 4. Weak Acid + Weak Base Reaction May or May Not Occur**
Normality and Acid-Base Chemitry 15
3 Types of Equations Can Describe Reaction 1. Complete Equation (complete chemical formulas) 2. Total Ionic Equation (what exist as soln) 3. Net Ionic Equation (ions that do something) 16 1. Complete Equation 2. Total Ionic Equation 3. Net Ionic Equation
What is the net ionic equation for the reaction of magnesium hydroxide with sulfuric acid? 17 1. Complete Equation 2. Total Ionic Equation 3. Net Ionic Equation
Simplified 18 Reactants Net Ionic Equation
If the following weak acids and weak bases are mixed will a reaction occur? If a reaction occurs, give the balanced chemical equation. 19
Acid Base Reaction with Gas Formation 20 In Solution or solid S 2- + 2H 3 O + (aq) H 2 S(g) + 2H 2 O(l) SO 3 2- + 2H 3 O + (aq) H 2 SO 3 (aq) + 2H 2 O(l) H 2 SO 3 (aq) H 2 O(l) + SO 2 (g) HSO 3 - + H 3 O + (aq) H 2 SO 3 (aq) + H 2 O(l) H 2 SO 3 (aq) H 2 O(l) + SO 2 (g) CO 3 2- + 2H 3 O + (aq) H 2 CO 3 (aq) + 2H 2 O(l) H 2 CO 3 (aq) H 2 O(l) + CO 2 (g) HCO 3 - + H 3 O + (aq) H 2 CO 3 (aq) + 2H 2 O(l) H 2 CO 3 (aq) H 2 O(l) + CO 2 (g) NH 4 + (aq) + OH - (aq) NH 3 (g) + H 2 O(l)
IV. Oxidation-Reduction Reactions 21 So Far 1. Ionic(aq) + Ionic(aq) Transfer of ions 2. Acid + Base Transfer of acidic H s 3. Oxidation Reduction Transfer of e - Reactions Terminology Oxidation - Reduction - when a lone atom or atom within a molecule or ion loses an electron(s) when a lone atom or atom within a molecule or ion gains an electron(s) Reducing Agent - element that forces another element to gain electrons Oxidizing Agent - element that forces another element to lose electrons
22 A. Recognition (Oxidation States) Keeping Track of Electrons Oxidation State (#) Rules For Obtaining Oxidation States 1. Each atom in a neutral cmpd. containing only one type of element has an ox. st. = 0 2. For monoatomic ions, the ox. st. is equal to the charge on the ion
Keeping Track of Electrons Cont d 3. In its compounds and ions, the following elements usually have a specific ox. st. 23 A. Fluorine (F) - when combined with other, different elements, F always has an ox. st. = -1 B. Hydrogen (H) - when combined with other, different elements, H usually has an ox. st. = +1 C. Oxygen (O) - when combined with other, different elements, O usually has an ox. st. = -2