Ch. 15 Solutions Problem Set 15.1 Problem Set 15.2 Problem Set 15.3 Ch. 19 Acids and Bases

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1 Ch. 15 Solutions Problem Set 15.1 Solution terminology Why/how dissolving occurs Factors affecting rate of solvation vs. solubility Heats of solution Problem Set 15.2 Concentration (Molarity) problems Solution Preparation from solid from a concentrated solution Problem Set 15.3 Molecular, total ionic, and net ionic reactions Precipitation reactions (double replacement & solubility rules) Single replacement reactions Molarity and 3step mole method used in combination Be able to explain the following terms: phase, solute, solvent, solution, pure substance, homogeneous, heterogeneous, and solubility. Be able to explain the why a solute dissolves in only certain solvents. Be able to describe a system using the terms above. Be able to describe how a solution is prepared. Be able to express the concentration of a solution in terms of molarity (M) and calculate M for various solutions. Be able to calculate volume of a solution if given the number of moles of solute and Molarity of the solution. Be able to calculate moles of solute for a give volume and concentration of solution. If given an initial volume and concentration, be able to find the final concentration after a dilution. (Using the relationship M 1 V 1 = M 2 V 2.) (or if given final conditions, find initial concentration) Given an initial volume and concentration, be able to find the final volume needed to make a given concentration. (M 1 V 1 = M 2 V 2 ) (or if given final conditions, find initial volume) 3step moles method problems with molarity involved. Ch. 19 Acids and Bases Conductivity Demo species in solution (Ionic vs. Acids vs. Molecular) Dominant species (ions vs. molecules), number of species present in a solution Percent dissociation Electrolytes (strong, weak, and non) Conductivity ion conc. in solution (related to conc. solute AND strength of electrolyte) Ionization vs. dissociation (dissolving equations) Acid/Base selfionization of water Strong vs. weak acids Ammonia (NH 3 ) is a weak base total and net ionic reactions written with dominant species in solution (mostly ions vs. mostly molecules) Definition of Acids/Bases Arrhenius BronstedLowry conjugate acids/bases (& relative strengths) proton transfer reactions predict products/reactants side favored strongest acid/base Lewis Acid Strength (Ka, eletrolytes, dominant species) polyprotic acids (ionization equations, strength of) amphoteric species (water & anions of polyprotic acids) calculating [H+], [OH], and ph if given neutrality problem (titration) excess problem given concentration of a strong acid given concentration of a strong base

2 given moles and volume of an acid or base weak acid problems if given Ka s etc. etc... LeChatelier s Principle & equilibrium shifts Types of Reactions See Notes Handout Titration Lab indicators (phenolphthalein, litmus, universal) ph back titrating moles H + vs. moles OH neutrality problems excess problems equivalence point end point Review of Reaction Types Ch. 15 and 19 1) Double Replacement a. precipitation ex. b. neutralization Molecular: Pb(NO 3 ) KI PbI 2 (s) + 2 KNO 3 Total Ionic: Pb NO K I PbI 2 (s) + 2 K NO 3 Net Ionic: Pb I PbI 2 (s) w/strong acid ex. Molecular: 2 HNO 3 + Ca(OH) 2 2 H 2 O (s) + 2 Ca(NO 3 ) 2 Total Ionic: 2 H NO 3 + Ca OH 2 H 2 O (s) + Ca NO 3 Net Ionic: H + + OH H 2 O (s) w/weak acid ex. Molecular: HNO 2 + KOH 2 H 2 O (s) + 2 KNO 3 Total Ionic: HNO 2 + K + + OH H 2 O (s) + K + + NO 2 Net Ionic: HNO 2 + OH H 2 O (s) + NO 2 c. metal carbonate and acid molecular: CaCO 3 (s) + 2 HCl CaCl 2 + CO 2 (g) + H 2 O (l) total ionic: CaCO 3 (s) + 2 H Cl Ca Cl + CO 2 (g) + H 2 O (l) net ionic: CaCO 3 (s) + 2 H + Ca 2+ + CO 2 (g) + H 2 O (l) 2) Protontransfer (BronstedLowry type) examples a. HCl + H 2 O <==> H 3 O + + Cl b. OH + HF <==> F + H 2 O c. NH CN <==> NH 3 + HCN d. HSO 3 + HF <==> H 2 SO 3 + F 3) Acid + Metal (singlereplacement) molecular: Zn (s) + 2 HCl H 2 (g) + ZnCl 2 total ionic: Zn (s) + 2 H Cl H 2 (g) + Zn Cl net ionic: Zn (s) + 2 H + H 2 (g) + Zn 2+ Ionic Equations Write everything that exists mostly as ion as ions Write everything that exists mostly as molecules as molecules IONS Leave alone/keep together Soluble ionic compounds insoluble ionic compounds Strong acids Weak acids Molecular Compounds Elements

3 Reaction type? HCl + LiOH Na 2 SO 4 + PbCl 2 CaCO 3 + HNO 3 CH 3 COOH + Ca(OH) 2 Mg + HCl CN + HF HS + CN Ch. 15 Review Problems: 1) How many grams of Sodium phosphate (Na 3 PO 4 ) are needed to make 525 ml of a 2.30 M solution? 2) How many milliliters of a 2.0 M solution are needed to obtain 312 grams of NaCl? 3) How many moles are in 500. ml of a 2.0 M solution of AgNO 3? 4) If I want to obtain a 2.0 M solution, to what volume must I dilute the following combinations? a. 50. ml of a 6.0 M solution b. 25 ml of a 3.0 M solution 5) How many milliliters of a 3.0 M solution do I need to obtain the following? a ml of a 2.0 M solution b ml of a 1.0 M solution 6.) How many milliliters of a M solution contain each of the following: a mol MgCl 2 b mol of HCl c mol of Mn(NO 3 ) 2 7) 112 g of NaCl is dissolved in H 2 O to make 250 ml total volume. What is the concentration of the solution? 8.) How many moles of solute are present in 25 ml of a M solution? If my solute is MgCl 2, how many grams are present is this sample? 9) What is the concentration of the solution obtained when 50.0 ml of M solution is diluted to 110. ml? 10) How many grams of Na 2 CrO 4 should be dissolved in enough water to make one liter of a molar solution? 11) 2.05 grams of hydrogen gas are produced from the reaction of magnesium and a solution of hydrochloric acid. If 150. ml of acid are used, what must be its concentration? 12) 3.76 grams of precipitate are produced from the reaction of a mercury (II) nitrate solution and a solution of sodium hydroxide. If 150. ml of sodium hydroxide are used, what must be its concentration? 13) What 3 factors affect the rate of solvation? Which of these factors also change the amount that is able to dissolve? 14) a. How does increasing temperature affect the solubility of gas? b. How does decreasing temperature affect the solubility of gas? c. How does increasing temperature affect the solubility of a solid which dissolves endothermically? d. How does decreasing temperature affect the solubility of a solid which dissolves endothermically? e. How does increasing temperature affect the solubility of a solid which dissolves exothermically? f. How does decreasing temperature affect the solubility of a solid which dissolves exothermically? 15) Which of the following statements are true about increasing the temperature at which a reaction occurs? a. The reaction will occur at a faster rate. b. There will be more collisions between molecules in a given amount of time. c. The number of molecules that have sufficient energy to react in increased. d. The energy needed for the reaction to occur is decreased. e. The average kinetic energy of the molecules is greater. f. The activated complex is different than it would be at a lower temperature. g. The energy of the activated complex is lower.

4 Ch. 19 AcidBase Calculations 1) Convert between [H + ], [OH ], ph, and poh K w = [H + ][OH ] K w = 1 x ph = log [H + ] [H + ] = 10 ph 2) Do titration calculations i.e. Calculate the concentration of an unknown base (given the volume of base that neutralizes a known volume and molarity of acid) STEPS: 1) Calculate moles acid neutralized. 2) Moles base (OH ) is equal to moles acid (H + ) 3) M = n/v (divide moles base by volume of base to determine concentration) 3) Do Excess problems i.e. If given unequal moles of acid and base, calculate the resulting ph STEPS 1) Calculate initial moles of H + 2) Calculate initial moles of OH 3) Write out net ionic equation: H + + OH H 2 O 4) Use ICE chart to calculate excess moles of H + /OH 5) M = n/v; Calculate concentration of excess reagent by dividing by total volume 6) Calculate ph/poh REVIEW PROBLEMS: 1) Find [H + ] and [OH ] in 1.0 liter of: a M NaOH b M HCl 2.) In CH 3 COOH, what species is present in greatest concentration at equilibrium? How many total species are present? How about for pure water? 3.) Find [H +] and [OH ] if 50 ml of M NaOH and 50 ml of M HCl combine. Also find the ph. 4.) How much M NaOH will neutralize 50 ml of M HCl? 5.) For each of the following find the [H+], [OH], and ph. A M HNO 3 (Ka = very large) B M HNO 2 (Ka = 5.1 x 10 4 ) Only if Expt. #26 was done (Indicators) C ml of M HCl is mixed with 15.0 ml of M NaOH 6.) 25.0 ml of M HCl is just neutralized with 40.0 ml of NaOH. Find the concentration of the original NaOH solution. Directions: Calculate the [H+],[OH], and ph for each of the following. (Assume equilibrium is at 25 C.) M HCl M KOH 3. When moles of HNO 3 is dissolved in 200 ml of water.

5 [H + ] = [OH ] = ph = 4. When 1.2 moles of LiOH is dissolved in 250 ml of water M Ba(OH) M HClO moles of HCl is mixed with moles of NaOH in Liters of water ml of NaOH are required to neutralize.200 moles of HCl. What is the concentration of the NaOH? ml of Ca(OH) 2 are required to neutralize.150 moles of HCl. What s the concentration of Ca(OH) 2? 10) Which is false about M HBr? Which is false about M HF? a. [H+] = M d. turns phenolphthalein pink b. ph = 2.00 e. turns litmus pink c. exists completely as ions f. [OH] = 1.0 x M 11) Rank the following in order of increasing [H + ] NH 4 +, HS, H 2 O, H 2 SO 4, HCl, CH 3 COOH 12) Rank the following in order of increasing tendency to combine with H +. HS, NH 3, Cl, CH 3 COO EXCESS PROBLEMS: 13) 15.0 ml of M NaOH is mixed with 30.0 ml of M HCl. What s the ph of the resulting mixture? 14) 18.0 ml of M HBr is needed to neutralize 15.0 ml of NaOH. What s the concentration of the original NaOH solution? MIXED REVIEW (Titration/Excess): 15) 22.8 ml of 1.00 M Ba(OH) 2 just neutralized 32.0 ml of HI. What is the concentration of the original HI solution? 16) 18.5 ml of M HNO 3 is needed to neutralize 31.0 ml of Ba(OH) 2. What s the concentration of the original Ba(OH) 2 solution? 17) 23.0 ml of M HBr is mixed with 16.0 ml of M Ca(OH) 2. What s the ph of the resulting mixture? 18) 72.0 ml of KOH neutralizes mol HBr. What s the concentration of the KOH?