Ex3_S06_ans

Ex3_S06_ans - Name _A. Key_ Chem 114 Exam 3 Total Points =...

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Problem Session _All__ Chem 114 Exam 3 Dr. A. H. Martin Total Points = 105 March 24, 2006 Calculations must be shown for credit on ALL problems, and ALL dependent variables, i.e. x's, must be defined. (8)1. Indicate whether aqueous solutions of the following salts are Acidic , Basic , or Neutral . For each nonneutral salt, also give the chemical formula of the ion that causes the shift from neutrality. acidic, basic, or neutral ion causing change KHCO 3 ___basic_________ ____HCO 3 1- _________ C 2 H 5 NH 3 Br ___acidic__________________ _____C 2 H 5 NH 3 1+ _____ NaClO 4 ___neutral____________ ____neither_________ Ti(NO 3 ) 3 __acidic_____________ _____Ti 3+ ____________ (2) 2. Give equilibrium equation and equilibrium constant expression for the K sp for Fe 3 (PO 4 ) 2 . Fe 3 (PO 4 ) 2 3 Fe 2+ + 2 PO 4 3- K sp = [Fe 2+ ] 3 [PO 4 3- ] 2 (3) 3. Give the net ionic equation for the hydrolysis of the salt CH 3 NH 3 NO 3 . CH 3 NH 3 NO 3 CH 3 NH 3 1+ + NO 3 1- CH 3 NH 3 1+ CH 3 NH 2 + H 1+ (15) 4. A buffer solution is 0.70 M in HOCN and 0.50 M in NaOCN. Answer the following based on this buffer. (For HOCN K a = 3.5x10 -4 ) a) Give the chemical formula of the base form of the buffer. __OCN 1- ___________ b) Give the chemical formula for the acid form of the buffer. _____ HOCN _______________ c) Give the net ionic equation for the reaction of the buffer with Ca(OH) 2 . HOCN + OH 1- OCN 1- + H 2 O d) Give the net ionic equation for the reaction of the buffer with HI. OCN 1- + H 1+ HOCN e) Calculate the pH of the buffer. (Show your calculations.) πΗ = πΚ α + λογ [ΟΧΝ 1- ] [ΗΟΧΝ] = - λογ3.5ξ10 -4 + λογ (0.5029 (0.7029
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Ex3_S06_ans - Name _A. Key_ Chem 114 Exam 3 Total Points =...

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