Exam3_Review_ClickerQuestions
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Exam3_Review_ClickerQuestions

Course Number: CHEM 178, Fall 2008

College/University: Iowa State

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Chem 178 Class 22 Chem 178 Class 22 An aqueous solution of KCl would be Which one of these salts will form a basic solution upon dissolving in water? 57% 1. neutral 2. basic 3. acidic 28% 15% 1. 2. 3. 4. NaCl NaNO2 NH4NO3 KBr 59% 28% 12% 1% 2 aC l O 3 ut ra l aN O id ic si c ba ac ne N Chem 178 Class 22 Chem 178 N H 4N N K B r Class 22 Which one of these salts will form an acidic...

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178 Class Chem 22 Chem 178 Class 22 An aqueous solution of KCl would be Which one of these salts will form a basic solution upon dissolving in water? 57% 1. neutral 2. basic 3. acidic 28% 15% 1. 2. 3. 4. NaCl NaNO2 NH4NO3 KBr 59% 28% 12% 1% 2 aC l O 3 ut ra l aN O id ic si c ba ac ne N Chem 178 Class 22 Chem 178 N H 4N N K B r Class 22 Which one of these salts will form an acidic solution upon dissolving in water? Arrange the acids HBr, H2Se, and H3As in order of increasing acid strength. 1. 2. 3. 4. NaCl NaNO2 NH4NO3 KBr 96% 1% aC l aN O N 2% 2 O 3 1. 2. 3. 4. 5. 1% r B K HBr < H2Se < H3As HBr < H3As < H2Se H2Se < H3As < HBr H3As< H2Se < HBr H3As< HBr < H2Se H < 2S e H r< B B H H 81% 7% 3% .. . 9% 0% ... .. . H2 . Br < H < H .. .. . H < H3 A s s H < H 3A s< H H N H N H 3A s< r< 4N 2S e 2S e 3A < Chem 178 Class 22 Chem 178 Class 22 Arrange the acids H2Se, H2Te, and H2S in order of increasing acid strength 1. 2. 3. 4. 5. H2S < H2Se < H2Te H2S < H2Te < H2Se H2Te < H2S < H2Se H2Se< H2S < H2Te H2Se< H2Te < H2S H < When comparing acid strength of binary acids HX, as X varies within a particular group (i.e., column) of the periodic table, which one of these factors dominates in affecting the acid strength? 91% 2% ... ... H H 0% ... 1% H2 .. . 6% tro n 2S 2S 2T 2S bo 2S ec pe rc e Chem 178 H Class 22 Chem 178 el H Le H H H Ch e< 1. bond strength 2. electron withdrawing effects 3. percent ionic character of the H-X bond 4. solubility 5. Le Chtelier's principle 68% 16% 9% 5% 1% r's te li e ... H ... gt h d. .. . .. st re n H2 S w i th 2T e H2 S H2 T 2S io n nd < < e< e nt < so H H lu bi l it < < < e e < ic y Class 22 Arrange the acids HIO3, HClO3, and HBrO3 in order of increasing acid strength. Arrange the acids HOCl, HClO3, and HClO2 in order of increasing acid strength. 73% 1. 2. 3. 4. 5. HIO3 < HClO3 < HBrO3 HIO3 < HBrO3 < HClO3 HBrO3 < HIO3 < HClO3 HClO3 < HIO3 < HBrO3 HClO3 < HBrO3 < HIO3 Cl O 3 H < 3 3 IO IO H H 17% 6% 3% <. .. <. .. 1% <. .. .. . rO 3 1. 2. 3. 4. 5. HOCl < HClO3 < HClO2 HOCl < HClO2 < HClO3 HClO2 < HOCl < HClO3 HClO3 < HOCl < HClO2 HClO3 < HClO2 < HOCl lO HC < 3 lO HC HC l< l< O C O C 96% 0% 2 3 lO lO HC HC 1% 0% 3% 3 2 lO HC lO 3 < HC lO 2 < HO Cl <. .. HI O 3 Br O IO lO HO H < < < < rO 3 lO 3 < lO 3 lO 2 B C C C C lO 3 H < H C H H H H H H HO HB H Cl < < 2 Cl < 3 3 Chem 178 Class 22 Chem 178 Class 22 A solution is prepared by mixing 500. mL of 0.10 M NaOCl and 500. mL of 0.20 M HOCl. What is the pH of this solution? [Ka(HOCl) = 3.2 10-8] You are asked to go into the lab and prepare an acetic acid sodium acetate buffer solution with a pH of 4.00 0.02. What molar ratio of CH3COOH to CH3COONa should be used [pKa(CH3COOH) = 4.74] 1. 2. 3. 4. 5. 4.10 7.00 7.19 7.49 7.80 43% 28% 16% 10% 4% 1. 2. 3. 4. 5. 0.18 0.84 1.19 5.50 0.10 78% 13% 4% 5% 0% 5. 5 .1 7. 4. 1 7. 8 7. 19 7. 49 .1 8 .8 4 Chem 178 Class 22 Chem 178 1. 19 Class 22 What is the net ionic equation for the reaction that occurs when small amounts of hydrochloric acid are added to a HOCl/NaOCl buffer solution? Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 8.3-10.3? 43% 1. 2. 3. 4. 5. H+ + H2O H3O+ H+ + OCl- HOCl HOCl H+ + OClH+ + HOCl H2OCl+ HCl + HOCl H2O + Cl2 27% 14% 8% 8% 1. CH3COONa/CH3COOH (Ka = 1.8 10-5) 2. NH3/NH4Cl (Ka = 5.6 10-10) 3. NaOCl/HOCl (Ka = 3.2 10-8) 4. NaNO2/HNO2 (Ka = 4.5 10-4) 5. NaCl/HCl 3C O CH 81% 5% ... ... 9% 3% 3% a. .. Cl aC l/H Ka Ka ... Cl ( NO 4C l( 2 (K Na / 3/ NH l/H O aO C O O 3C N C H N aN O N H 2/ H N Chem 178 Class 22 Chem 178 Class 22 You have 500.0 mL of a buffer solution containing 0.20 M acetic acid (CH3COOH) and 0.30 M sodium acetate (CH3COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution? [Ka = 1.8 10-5] 50.00 mL of 0.10 M HNO2 (nitrous acid, Ka = 4.5 10-4) is titrated a with 0.10 M KOH solution. After 25.00 mL of the KOH solution is added, the pH in the titration flask will be 1. 2. 3. 4. 5. 4.41 4.74 4.56 4.92 5.07 4. 41 33% 22% 16% 22% 7% 1. 2. 3. 4. 5. 2.17 3.35 2.41 1.48 7.00 2% 2. 17 71% 14% 7% 5% 4. 74 5. 07 4. 56 4. 92 3. 35 2. 41 Chem 178 Class 22 Chem 178 1. 48 7. Class 22 For which type of titration will the pH be basic at the equivalence point? 1. 2. 3. 4. 5. Strong acid vs. strong base. Strong acid vs. weak base. Weak acid vs. strong base. all of the these none of these 2% .. .. ... ... Calculate the pH at the equivalence point for the titration of 100.0 mL of 0.20 M NH3 (Kb = 1.8 10-5) with 0.20 M HCl. 82% 14% 0% th e. .. vs 2% th es e 1. 2. 3. 4. 5. 2.87 4.98 5.12 7.00 11.12 45% 25% 20% 10% 0% 7. 2. 87 4. 98 5. 12 .1 2 11 vs id id vs lo ft he al ac id ac ac St ro ng St ro ng ea k W no ne of Chem 178 Class 22 Chem 178 Class 22 What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCl with 0.10 M NaOH? 100% The molar solubility of lead(II) iodate [Pb(IO3)2]in water is 4.0 10-5 mol/L. Calculate Ksp for lead(II) iodate 1. 2. 3. 4. 5. 1.0 6.0 7.0 8.0 13.0 0% 1. 1. 2. 3. 4. 5. 0% 0% 13 . 1.6 10-9 6.4 10-14 2.6 10-13 4.0 10-5 4.0 10-15 42% 25% 25% 8% 0% 0% 6. 7. Chem 178 8. Class 22 Chem 178 Class 22 Calculate the concentration of fluoride ions in a saturated barium fluoride (BaF2, Ksp = 1.7 10-6) solution. In which of these solutions would barium chromate (BaCrO4, Ksp = 2.1 10-10) be most soluble? (Note: Ka for HCrO4- = 3.0 10-7) 1. 2. 3. 4. 0.01 M HCl solution (pH = 2.0) Neutral water solution (pH = 7.0) 0.01 M NaOH solution (pH = 12.0) 0.01 M NaCrO4 solution (NaCrO4 is highly soluble) tio n ol u 1. 2. 3. 4. 5. 7.6 10-3 M 1.5 10-2 M 3.4 10-5 M 1.7 10-6 M 3.4 10-6 M 86% 72% 11% 11% 6% ti. . 10% ol ut io n. ut io so l H 0. 01 M Na C n. .. rO 4 (.. .. 5% ls er s M tra l 01 0. eu N 0. 01 M Na O w at HC so lu 0% 0% Chem 178 Class 22 Chem 178 Complete and balance the following redox equation. H2S + HNO3 S + NO (acidic solution) When properly balanced using the smallest whole-number coefficients, the coefficient of S is Complete and balance the following redox equation. Bi(OH)3 + SnO22- Bi + SnO32- (basic solution) The sum of the smallest whole-number coefficients is 33% 33% 33% Class 22 1. 2. 3. 4. 5. 1 2 3 5 6 0% 100% 1. 2. 3. 4. 5. 0% 2 3 9 12 18 21 none of these 9 0% 12 18 21 0% th es e of 0% 5 0% 6 Chem 178 1 Class 22 Chem 178 no ne Class 22 For the reaction Ni2+(aq) + 2Fe2+(aq) Ni(s) + 2Fe3+(aq), the standard cell potential Ecell is According to the following cell diagram, which chemical species undergoes reduction? Sn | Sn2+ || NO3- (acid soln), NO(g) | Pt 1. 2. 3. 4. 5. +2.81 V +1.02 V +0.52 V -1.02 V -2.81 V. 0% V .0 2 .8 1 63% 38% 1. 2. 3. 4. 5. 0% V. .8 1 Sn Sn2+ NO3NO Pt 67% 11% 0% 2+ O 3Sn Sn 11% 11% 0% V V .5 2 .0 2 V +2 +1 +0 -1 -2 N N Pt O Chem 178 Consider an electrochemical cell based on the following cell diagram: Pt | Pu3+(aq), Pu4+(aq) || Cl2(g), Cl-(aq) | Pt Given that the standard cell emf is 0.35 V, what is the standard reduction potential E(Pu4+/Pu3+)? 75% Class 22 Chem 178 Consider the following standard reduction potentials in acid solution: Class 22 The strongest oxidizing agent among those shown above is 1. 2. 3. 4. 5. 2.37 V 1.01 V -1.71 V -1.01 V 1.71 V V 37 2. 25% 0% V 01 .7 1 0% V 0% V .0 1 71 V 1. 2. 3. 4. 5. Fe3+ Fe2+ BrAl3+ Al 67% 11% 0% 11% 11% 1. -1 -1 1. l3 + 3+ 2+ r- Fe Fe B Chem 178 Class 22 Chem 178 A A l Class 22 Which one of the following reagents is capable of transforming Cu(s) to Cu2+(1 M)? For the electrochemical cell Ni(s) | Ni2+(1 M) || H+(1 M) | H2(1 atm) | Pt(s), which one of the following changes will cause a decrease in the cell voltage? 1. Increase the pressure of H2 to 2.0 atm 2. Decrease the mass of the nickel electrode 3. Lower the pH of the cell electrolyte 4. Decrease the concentration of Ni2+ ion 5. none of these 60% 1. 2. 3. 4. 5. I- (1 M) Ni(s) Ag+(1 M) Al3+(1 M) H+(1 M) 0% ) M (1 N I- 50% 25% 20% 10% 10% 0% p. .. o. .. ... .. th e c. no ne th es e of m th e 13% 13% th e th e pH D ec re a se M ) i(s M ) M cr ea re a se g+ (1 l3 + In H ec A D Lo A w er (1 +( 1 se ) )
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