Final MWF-solutions - Version 336 Final MWF sutcliffe...

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Unformatted text preview: Version 336 Final MWF sutcliffe (50965) 1 This print-out should have 46 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Methane (CH 4 ) forms a molecular solid. What type of forces hold it in a solid con- figuration? I) London forces II) dipole-dipole forces III) hydrogen bonding 1. II only 2. I only correct 3. I and II only 4. III only 5. II and III only 6. I, II, and III Explanation: Solid methane is held together only by Lon- don forces. 002 10.0 points Which of the following elements is not cor- rectly paired with its group (family) name? 1. Strontium (Sr), Alkaline earth metals 2. Radon (Rn), Noble gases 3. Lithium (Li), Alkali metals 4. Bismuth (Bi), Halogens correct Explanation: The pnictogens are the family containing nitrogen through bismuth. The halogens are fluorine through astatine. 003 10.0 points Write the formula unit equation for this re- action occurring in water: Sodium phos- phate and calcium chloride are mixed to form sodium chloride and calcium phosphate. 1. 2 Na 3 PO 4 (aq) + 3 CaCl 2 (aq) 6 NaCl (aq) + Ca 3 (PO 4 ) 2 (s) correct 2. Na 2 PO 4 (s) + CaCl 2 (aq) 2 NaCl (aq) + CaPO 4 (s) 3. 2 Na 3 PO 4 (aq) + 3 CaCl 2 (s) 6 NaCl (aq) + Ca 3 (PO 4 ) 2 (s) 4. NaPO 4 (aq) + CaCl(aq) NaCl (aq) + CaPO 4 (s) 5. Na 2 PO 4 (aq) + CaCl 2 (aq) 2 NaCl (aq) + CaPO 4 (s) 6. 2 Na 3 PO 4 (s) + 3 CaCl 2 (aq) 6 NaCl (aq) + Ca 3 (PO 4 ) 2 (s) Explanation: 004 10.0 points Calculate the change in entropy when 2.00 moles of methane are compressed isother- mally to one fifth of its original volume. Treat methane as an ideal gas. 1.- 1.39 J K 1 2. +13.4 J K 1 3.- 26.8 J K 1 correct 4. +26.8 J K 1 5.- 13.4 J K 1 Explanation: If compressed to one fifth the original vol- ume this means V 2 = V 1 5 or V 2 V 1 = 1 5 S = nR ln parenleftbigg V 2 V 1 parenrightbigg = (2 . 00 mol)(8 . 314 J mol 1 K 1 ) ln parenleftbigg 1 5 parenrightbigg =- 26 . 7617 J K 1 Version 336 Final MWF sutcliffe (50965) 2 We expect a negative answer since the volume decreased. 005 10.0 points How many oxygen atoms (not molecules) are present in 1.25 moles of SO 2 ? 1. 1 . 50 10 24 atoms correct 2. 1.25 atoms 3. 7 . 52 10 23 atoms 4. 2.50 atoms Explanation: n = 1.25 mol In one mole of SO 2 , there are 2 moles of oxygen atoms. We can use this ratio to con- vert from moles of SO 2 to moles of oxygen atoms: ? mol O = 1 . 25 moles SO 2 2 mol O 1 mol SO 2 = 2 . 5 mol O We use Avogadros number to convert from moles of oxygen atoms to the number of indi- vidual oxygen atoms: ? atoms O = 2 . 5 mol O 6 . 02 10 23 atoms O 1 mol O = 1 . 505 10 24 atoms O 006 10.0 points Which of the following would probably have a positive S value?...
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Final MWF-solutions - Version 336 Final MWF sutcliffe...

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