exam final_solutions

exam final_solutions - Version 263 – Final – Sutcliffe...

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Unformatted text preview: Version 263 – Final – Sutcliffe – (53770) 1 This print-out should have 45 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. This exam is for Dr. Sutcliffes TTh section only. PLEASE double check all of your bub- bling carefully as we wont have much time to fix EID and version number errors afterwards. Good luck and have a great holiday! 001 10.0 points A gaseous mixture made from 6.00 grams of oxygen gas and 9.00 grams of chlorine gas is placed in a 15.0 L vessel at 10.0 degrees Celsius. What is the total pressure in the vessel? 1. 1.00 atm 2. 0.800 atm 3. 0.244 atm 4. 0.488 atm correct 5. 0.655 atm Explanation: 002 10.0 points If sufficient acid is used to react completely with 10 . 5 grams of Mg, Mg(s) + 2 HCl(aq) → MgCl 2 (aq) + H 2 (g) what volume of hydrogen at STP would be produced? 1. 19.4 liters 2. 9.7 liters correct 3. 5.0 liters 4. 22.4 liters 5. 10.3 liters Explanation: n H 2 = 10 . 5 g Mg · mol Mg 24 g Mg · 1 mol H 2 1 mol Mg = 0 . 4375 mol H 2 T = 0 ◦ C = 273 . 15 K P = 1 atm We can use the ideal gas law P V = nRT V = nRT P = (0 . 4375 mol) ( . 08206 L · atm K · mol ) 1 atm × (273 . 15 K) = 9 . 80643 L 003 10.0 points A reaction for which Δ H is negative and Δ S is negative 1. could become spontaneous at high tem- peratures. 2. is not spontaneous at any temperature. 3. is spontaneous at any temperature. 4. could become spontaneous at low temper- atures. correct Explanation: Δ G = Δ H- T Δ S Δ H < 0 and Δ S < 0. T is always positive so Δ G = Δ H- T Δ S = (- )- T (- ) = (- ) + T If the temperature is high enough, Δ G will be positive. 004 10.0 points What is the de Broglie wavelength of a flea midway through its jump? Assume the mass of the flea is 4 . 50 × 10 − 4 g and it is moving at 1.00 m/s. 1. 1 . 4725 × 10 − 30 m 2. 2 . 9818 × 10 − 40 m 3. 1 . 47244 × 10 − 27 m correct Version 263 – Final – Sutcliffe – (53770) 2 4. 2 . 9818 × 10 − 37 m Explanation: m = 0 . 00045 g × . 001 kg 1 g = 4 . 5 × 10 − 7 kg λ = h p = h m · v = 6 . 626 × 10 − 34 kg · m 2 s (4 . 5 × 10 − 7 kg)(1 m / s) = 1 . 47244 × 10 − 27 m 005 10.0 points Which of the following is the best represen- tation of the compound calcium sulfide? 1. None is appropriate because calcium sul- fide is a covalent compound. 2. Ca 2+ , 2 bracketleftbigg S b b b b b b b b bracketrightbigg − 3. 2 Ca + , bracketleftbigg S b b b b b b b b bracketrightbigg 2 − 4. Ca 2+ , bracketleftbigg S b b b b b b b b bracketrightbigg 2 − correct 5. 3 Ca 2+ , 2 bracketleftbigg S b b b b b b b b bracketrightbigg 3 − 6. Ca + , bracketleftbigg S b b b b b b b b bracketrightbigg − Explanation: The metal loses all of its outer (valence) electrons; the non-metal gains sufficient elec- trons to form an octet. The ratio of the negative and positive ions is chosen so there is no overall charge....
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exam final_solutions - Version 263 – Final – Sutcliffe...

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