Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Chemistry FIFTH EDITION by Steven S. Zumdahl University of Illinois

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 2 Chemistry FIFTH EDITION Chapter 4 Types of Chemical Reactions and Solution Stoichiometry Don’t forget Homework!!!!

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 3 Section 4.3 The Composition of Solutions Important to know the Amount of Chemicals present in a Solution.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 4 Molarity Molarity (M) = moles of solute per volume of solution in liters:

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 5 Recall 1.0 M NaCl means 1 mole of solid NaCl is dissolved in enough water to make 1.0 L of solution. The solution contains 1 mole of Na + ions and 1 mole of Cl - ions in 1.0 L of solution.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 6 Standard Solution Solution whose concentration is accurately known.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 7 Figure 4.10 Preparation of a Standard Solution

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 8 Dilution Solutions are often prepared by diluting more concentrated solutions.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 9 Common Terms of Solution Concentration Stock - routinely used solutions prepared in concentrated form. Concentrated - relatively large ratio of solute to solvent. (5.0 M NaCl) Dilute - relatively small ratio of solute to solvent. (0.01 M NaCl)

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 10 “Solutions by Dilution” Moles of solute after dilution EQUALS Moles of solute before dilution M 2 x V 2 = M 1 x V 1

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 11 Figure 4.11 (a) A Measuring Pipet(b) A Volumetric (transfer) Pipet

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 12 Section 4.4 Types of Solution Reactions 4 Precipitation reactions AgNO 3 (aq) + NaCl(aq)  AgCl(s) + NaNO 3 (aq) 4 Acid-base reactions NaOH(aq) + HCl(aq)  NaCl(aq) + H 2 O(l) 4 Oxidation-reduction reactions Fe 2 O 3 (s) + Al(s)  Fe(l) + Al 2 O 3 (s)

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 13 Section 4.5 Precipitation Reactions Two solutions are mixed and an insoluble (solid) substance forms. Solid forms is called the precipitate. READ Carefully pages 140 – 145.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 14 Precipitation Reactions 1. Consider species present in each reactant sol’n., i.e., before the reaction occurs. 2. When the sol’ns are mixed, think in terms of ion exchange. Possible precipitates?? 3. Apply solubility rules.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 15 Simple Rules for Solubility 1.Most nitrate (NO 3  ) salts are soluble. 2.Most alkali (group 1A) salts and NH 4 + are soluble. 3.Most Cl , Br , and I  salts are soluble (NOT Ag +, Pb 2+, Hg 2 2+ )

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 16 Simple Rules for Solubility (p. 144) 4.Most sulfate salts are soluble (NOT BaSO 4, PbSO 4, HgSO 4, CaSO 4 ) 5.Most OH  salts are only slightly soluble (NaOH, KOH are soluble, Ba(OH) 2, Ca(OH) 2 are marginally soluble) 6.Most S 2 , CO 3 2 , CrO 4 2 , PO 4 3  salts are only slightly soluble.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 17 Figure 4.14 The Reaction of K 2 CrO 4 (aq) and Ba(NO 3 ) 2 (aq)

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 18 Figure 4.16 The Reaction of KCl(aq) and AgNO 3 (aq) Precipitate is AgCl

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 19 Describing Reactions in Solution 1.Molecular equation (reactants and products as compounds) AgNO 3 (aq) + NaCl(aq)  AgCl(s) + NaNO 3 (aq) 2.Complete ionic equation (all strong electrolytes shown as ions) Ag + (aq) + NO 3  (aq) + Na + (aq) + Cl  (aq)  AgCl(s) + Na + (aq) + NO 3  (aq)

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 20 Describing Reactions in Solution (continued) 3.Net ionic equation (show only components that actually react) Ag + (aq) + Cl  (aq)  AgCl(s) Na + and NO 3  are spectator ions.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 21 Stoichiometry of Precipitation Reactions Identify the species present in the combined solution, and determine what rxn. occurs. Write the balanced net ionic equation. Calculate the moles of reactants. Determine which reactant is limiting. Calculate the moles of product or products. Convert to grams or other units, as required.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 22 Homework Let’s do some practice problems together

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 23 Section 4.8 Acid – Base Reaction Arrhenius concept of acids and bases. Bronsted-Lowry concept of acids and bases. Also called Neutralizations Reactions. H + (aq) + OH - (aq)  H 2 O

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 24 Models of Acids and Bases Arrhenius Concept: Acids produce H + in aqueous solution, Bases produce OH  in aqueous solution. Brønsted-Lowry: Acids are proton (H + ) donors, Bases are proton acceptors. HCl + H 2 O  Cl  + H 3 O + acid base

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 25 Acid – Base Reaction Water is a non-electrolyte. Large quantities of H + & OH - cannot coexist in solution. They react to form water. H + (aq) + OH - (aq)  H 2 O Also, OH - has a strong enough affinity to strip H + ions from weak acids.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 26 Neutralization Reactions When enough base has been added to exactly react with the acid in a solution, then it is said that the acid has been neutralized.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 27 Performing Calculations for Acid-Base Reactions 1.List initial species and predict reaction. 2.Write balanced net ionic reaction. 3.Calculate moles of reactants. 4.Determine limiting reactant. 5.Calculate moles of required reactant/product. 6.Convert to grams or volume, as required.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 28 Acid – Base Titration Type of Volumetric Analysis: technique for determining the amt. of a certain substance by doing a titration. Titration: delivery from a buret of a measured volume of a solution of known concentration into a solution containing the substance being analyzed.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 29 Key Titration Terms Titrant - solution of known concentration used in titration Analyte - substance being analyzed Equivalence point - enough titrant added to react exactly with the analyte Endpoint - the indicator changes color so you can tell the equivalence point has been reached.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 30 Figure 15.6 Common Indicator: The Acid and Base Forms of the Indicator Phenolphthalein Let’s do some exercises!

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 31 Don’t forget your Homework!!