Exam 2 - CHM 2046 Gower/Mitchell Sections Exam 2 (Form Code...

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CHM 2046 Gower/Mitchell Sections Exam 2 (Form Code A) Spring 2010 Instructions: On your scantron sheet enter and bubble in your name , UF ID number (start on the leftmost space and leave any extra spaces blank), and Form Code (see above). Bubbling errors will not be negotiated . Note: A double-arrow symbol used in this exam ( ↔) refers to a reversible reaction. Potentially Useful Information: R = 0.0821 lit•atm/mol•K and 8.314 J/mol•K 1 F = 96,500 C/mol e 1V = 1J/C 1A = 1C/s 1. Calculate the molar solubility of PbCl 2 ( K sp = 1.7 x 10 –5 at 25ºC) in a solution that is 0.50 M NaCl. (1) 6.8 x 10 –5 mol/L (2) 3.4 x 10 –5 mol/L (3) 4.1 x 10 –3 mol/L (4) 2.0 x 10 –3 mol/L (5) 8.5 x 10 –6 mol/L 2. Calculate the molar solubility of Mn(OH) 2 ( K sp = 4.6 x 10 –14 at 25ºC) at a pH of 11.00. (1) 2.3 x 10 –14 mol/L (2) 1.0 x 10 –6 mol/L (3) 4.6 x 10 –1 mol/L (4) 4.6 x 10 –8 mol/L (5) 2.3 x 10 –7 mol/L 3. Consider the following equilibrium: AgCl(s) + 2 S 2 O 3 2– (aq) Ag(S 2 O 3 ) 2 3– (aq) + Cl (aq) If the K eq for the reaction above = 3.6 x 10 3 , and the K sp of AgCl = 1.8 x 10 –10 , calculate the K f of Ag(S 2 O 3 ) 2 3– . (1) 6.5 x 10 –7 (2) 2.0 x 10 13 (3) 5.0 x 10 –14 (4) 3.6 x 10 3 (5) 6.4 x 10 11 4. What will happen when a chemistry student mixes 20.0 mL of 4.5 x 10 –3 M AgNO 3 with 10.0 mL of 7.5 x 10 –2 M NaBrO 3 ? The K sp for AgBrO 3 = 6.7 x 10 –5 . (1) Q < K sp , so precipitation occurs until Q = K sp (2) Q > K sp , so precipitation occurs until Q < K sp (3) Q > K sp , so precipitation occurs until Q = K sp (4) Q < K sp , so precipitation occurs until Q > K sp (5) Q = K sp , so precipitation occurs until Q < K sp 5. For reactions a,b, and c below, indicate whether entropy increases or decreases from left to right: a. 2 CO 2 (g) 2 CO(g) + O 2 (g) b. NaCl(s) NaCl(aq) c. MgCO 3 (s) → MgO(s) + CO 2 (g) (1) a. decreases, b. increases, c. increases (2) a. increases, b. decreases, c. increases (4) a. increases, b. increases, c. decreases (4) a. increases, b. increases, c. increases (5) a. increases, b. decreases, c. decreases 6. Calculate the temperature (in ºC) to which silver ore, Ag 2 O, must be heated to spontaneously decompose the ore to oxygen gas and solid silver metal at standard state. f of Ag 2 O(s) = –31.05 kJ/mol;
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Exam 2 - CHM 2046 Gower/Mitchell Sections Exam 2 (Form Code...

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