Chemistry 1A - Chapter 5 Exercise Key

Transcription

1 Chemistry 1A - Chapter 5 Exercise Key Exercise 5.1 Ionic Solubility: Predict whether each of the following is soluble or insoluble in water. a. Hg(NO ) 2 soluble b. FeCO insoluble c. SnS insoluble d. K PO soluble e. PbCl 2 insoluble f. Al(OH) insoluble Exercise 5.2 Precipitation Reactions: Predict whether a precipitate will form when each of the following pairs of water solutions are mixed. If there is a precipitation reaction, write the complete, complete ionic, and net ionic equations that describe the reaction. a. Li 2 CO (aq) + 2Al(NO ) (aq) 6LiNO (aq) + Al 2 (CO ) (s) 6Li + (aq) + CO 2 (aq) + 2Al + (aq) + 6NO (aq) 6Li + (aq) + 6NO (aq) + Al 2 (CO ) (s) CO 2- (aq) + 2Al + (aq) Al 2 (CO ) (s) b. KOH(aq) + Fe(NO ) (aq) KNO (aq) + Fe(OH) (s) K + (aq) + OH (aq) + Fe + (aq) + NO (aq) K + (aq) + NO (aq) + Fe(OH) (s) OH (aq) + Fe + (aq) Fe(OH) (s) c. NaC 2 H O 2 (aq) + CaS(aq) No Reaction d. K 2 SO (aq) + Pb(NO ) 2 (aq) 2KNO (aq) + PbSO (s) 2K + (aq) + SO 2 (aq) + Pb 2+ (aq) + 2NO (aq) 2K + (aq) + 2NO (aq) + PbSO (s) SO 2 (aq) + Pb 2+ (aq) PbSO (s)

2 Exercise 5. Acid and Base Classification: Identify each of the following as either (1) an Arrhenius strong acid, (2) an Arrhenius weak acid, () an Arrhenius strong base, () an Arrhenius weak base, or (5) not acidic or basic in the Arrhenius sense (neutral). a. HNO 2 weak acid b. lithium hydroxide strong base c. NaCN weak base d. sodium iodide neutral e. NaHSO weak acid f. nitric acid strong acid g. CH OH neutral h. hydrofluoric acid weak acid i. KC 2 H O 2 weak base Exercise 5. Strong, Weak, and Nonelectrolyte: Each of the following substances dissolve in water. Identify each of the following as either a (1), (2) weak electrolyte, or () nonelectrolyte, and in parentheses write the type of compound each name or formula represents. Al(NO ) acetic acid NH ammonium acetate HCl(aq) glucose CH OH barium chloride K 2 Cr 2 O 7 nitric acid HBrO 2 2-propanol (or isopropyl alcohol) weak electrolyte weak electrolyte nonelectrolyte nonelectrolyte weak electrolyte nonelectrolyte

3 Exercise 5.5 Writing Neutralization Equations: For each of the following pairs of possible reactants, predict whether a neutralization reaction will take place between them. If there is no reaction, write, No Reaction. If there is a reaction, write complete, complete ionic, and net ionic equations for the reaction. (The reactions between weak acids and weak bases given here are reversible reactions. If an acid has more than one acidic hydrogen, assume that there is enough base to remove all of them. Assume that there is enough acid to add as many protons to the base as possible.) a. HCl(aq) + NaOH(aq) H 2 O(l) + NaCl(aq) H + (aq) + Cl (aq) + Na + (aq) + OH (aq) H 2 O(l) + Na + (aq) + Cl (aq) H + (aq) + OH (aq) H 2 O(l) b. HF(aq) + LiOH(aq) H 2 O(l) + LiF(aq) HF(aq) + Li + (aq) + OH (aq) HF(aq) + OH (aq) H 2 O(l) + F (aq) c. NH (aq) + HNO (aq) NH NO (aq) NH (aq) + H + (aq) + NO (aq) NH (aq) + H + (aq) NH + (aq) H 2 O(l) + + Li + (aq) + F (aq) NH + (aq) + NO (aq) d. NH (aq) + HClO(aq) NH ClO(aq) NH (aq) + HClO(aq) NH + (aq) + ClO (aq) NH (aq) + HClO(aq) NH + (aq) + ClO (aq) e. HC 2 H O 2 (aq) + LiF(aq) HF(aq) + LiC 2 H O 2 (aq) HC 2 H O 2 (aq) + Li + (aq) + F (aq) HF(aq) + Li + (aq) + C 2 H O 2 (aq) HC 2 H O 2 (aq) + F (aq) HF(aq) + C 2 H O 2 (aq) f. Na 2 CO (aq) + 2HBr(aq) 2NaBr(aq) + H 2 O(l) + CO 2 (g) 2Na + (aq) + CO 2 (aq) + 2H + (aq) + 2Br (aq) CO 2 (aq) + 2H + (aq) H 2 O(l) + CO 2 (g) g. HCl(aq) + HNO 2 (aq) No reaction - both acids 2Na + (aq) + 2Br (aq) + H 2 O(l) + CO 2 (g) h. H PO (aq) + LiOH(aq) H 2 O(l) + Li PO (aq) H PO (aq) + Li + (aq) + OH (aq) H 2 O(l) + Li + (aq) + PO (aq) H PO (aq) + OH (aq) H 2 O(l) + PO (aq)

4 i. Fe(OH) (s) + HNO (aq) Fe(NO ) (aq) + H 2 O(l) Fe(OH) (s) + H + (aq) + NO (aq) Fe + (aq) + NO (aq) + H 2 O(l) Fe(OH) (s) + H + (aq) Fe + (aq) + H 2 O(l) j. NaI(aq) + HCl(aq) No reaction - no base Exercise Brønsted-Lowry Acids and Bases: For each of the following equations, identify the Brønsted-Lowry acid and base. a. HNO 2 (aq) + NaBrO(aq) HBrO(aq) + NaNO 2 (aq) B/L acid B/L base b. H 2 PO - (aq) + HNO 2 (aq) H PO (aq) + NO 2 (aq) B/L base B/L acid c. H 2 PO - (aq) + 2OH (aq) PO - (aq) + 2H 2 O(l) B/L Acid B/L base d. H 2 SO (aq) + 2NaOH(aq) Na 2 SO (aq) + 2H 2 O(l) B/L Acid B/L base Exercise 5.7 Oxidation Numbers: Determine the oxidation number for the atoms of each element in the following formulas. Formula Oxidation Numbers P P is 0. PF P is +, and F is 1. PH P is -, and H is +1. P 2 O P is +, and O is 2. H PO H is +1, P is +5, and O is 2. N 2 N is 0. N N is. K N K is +1, and N is. Co N 2 Co is +2, and N is. NaH Na is +1, and H is 1. Na Na is O. HSO H is +1, S is +, and O is 2. Cu(NO ) 2 Cu is +2, N is +5, and O is 2. Cu (PO ) 2 Fe is +, S is +6, and O is 2.

5 Exercise 5.8 Redox Reactions: Identify whether the following equations describe redox reactions or not. For each of the redox reactions, identify what is oxidized, what is reduced, what the reducing agent is, and what the oxidizing agent is. a. Ca(s) + F 2 (g) CaF 2 (s) Ca goes from 0 to +2. F goes from 0 to 1. Yes, it s redox Ca is oxidized, and is the reducing agent. F is reduced and is the oxidizing agent. b. CaCO (s) CaO(s) + CO 2 (g) Ca goes from +2 to +2. C goes from + to +. All O s are 2. This is not redox. c. 2Al(s) + H 2 O(g) Al 2 O (s) + H 2 (g) Al goes from 0 to +. H goes from +1 to 0. All O s are 2. Yes, it s redox Al is oxidized, and is the reducing agent. H in H 2 O is reduced, so H 2 O is the oxidizing agent. d. Cr 2 O 7 2 (aq) + 6Cl (aq) + 1H + (aq) 2Cr + (aq) + Cl 2 (g) + 7H 2 O(l) Cr goes from +6 to +. Cl goes from 1 to 0. All H s are +1. All O s are 2. Yes, it s redox Cl in Cl is oxidized, so Cl is the reducing agent. Cr in Cr 2 O 7 2 is reduced, so Cr 2 O 7 2 is the oxidizing agent. e. 5H 2 C 2 O (aq) + 2KMnO (aq) + H 2 SO (aq) 10CO 2 (g) + 2MnSO (aq) + 8H 2 O(l) + K 2 SO (aq) C goes from + to +. Mn goes from +7 to +2. All H s are +1. All O s are 2. All S s are +6. Yes, it s redox C in H 2 C 2 O is oxidized, so H 2 C 2 O is the reducing agent. Mn in KMnO is reduced, so KMnO is the oxidizing agent.

6 Exercise 5.9 Stoichiometry and Molarity: How many milliliters of 6.00 M HNO are necessary to neutralize the carbonate in 75.0 ml of M Na 2 CO? mol Na CO 2 mol HNO 10 ml HNO soln = 6.25 ml HNO soln ml Na 2CO 1 mol Na 2CO 6.00 mol HNO? ml HNO soln = 75.0 ml Na CO Exercise Molarity: What is the molarity of a AgClO solution made by dissolving g of silver perchlorate in water and diluting with water to ml total?? mol AgClO g AgClO 1 mol AgClO 10 ml Molarity = = 1 L AgClO soln 50.0 ml AgClO soln g AgClO 1 L 2.89 mol AgClO 1 L AgClO soln = = 2.89 M AgClO Exercise 5.11 General Stoichiometry: What is the maximum number of grams of silver chloride that will precipitate from a solution made by mixing ml of M MgCl 2 with an excess a AgNO solution?? g AgCl = 25.0 ml MgCl mol MgCl 2 mol AgCl g AgCl ml MgCl2 1 mol MgCl 2 1 mol AgCl = 0.6 g AgCl Exercise 5.12 Titration Problem: When.2 ml of a 1.02 M NaOH solution is added from a burette to ml of a phosphoric acid solution that contains phenolphthalein, the solution changes from colorless to red. a. What is the titrant for this process? NaOH is the titrant. b. What is the molarity of the phosphoric acid?? mol HPO.2 ml NaOH soln 1.02 mol NaOH 1 mol HPO 10 ml = L HPO soln ml HPO soln 10 ml NaOH soln mol NaOH = 0.65 M HPO 1 L Exercise 5.1 Making solution from Solid: An experiment calls for a total of 1.50 L of M KMnO for a class of chemistry students. How would this solution be made from pure, solid potassium permanganate and water? mol KMnO g KMnO? g KMnO = 1.50 L soln 1 L soln = 7. g KMnO 1 mol KMnO Dissolve 7. g KMnO in a minimum amount of water and dilute with water to 1.50 L total.

7 Exercise 5.1 Dilution Problems: What is the molarity of a solution made by diluting 5.00 ml of a 1.8 M NH solution to 75.0 ml?? mol NH 5.00 ml conc. soln 1.8 mol NH 10 ml = L dil. soln ml dil. soln 10 ml conc. soln 1 L or MCVC 1.8 M ( 5.00 ml) MCV C = MDV D M D = = V 75.0 ml D = M NH Exercise 5.15 Making solution from Concentrated Acid: How would you make milliliters of 2.00 M acetic acid from concentrated acetic acid (called glacial acetic acid) that is 17. M HC 2 H O 2? 2.00 mol HC2HO2 10 ml conc. soln? ml conc. soln = ml dil. soln 10 ml dil. soln 17. mol HC2HO2 or M V D D MCV C = MDV D V C = = MC ( ) 2.00 M ml 17. M = 28.7 ml conc. soln Carefully add 28.7 ml of 17. M HC 2 H O 2 to about 200 ml of water, mix, and dilute with water to ml total. Exercise Making solution from More Concentrated Solution: How would you make 50.0 milliliters of M hydrochloric acid from 2.0 M HCl? mol HCl 10 ml conc. soln? ml conc. soln = 50.0 ml dil. soln 10 ml dil. soln 2.0 mol HCl or M V D D MCV C = MDV D V C = = MC ( ) M 50.0 ml 2.0 M = 6. ml conc. soln Add enough water to 6. ml 2.0 M HCl to yield a total volume of 50.0 ml

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