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Unformatted text preview: Chemistry 105 Exam IV Spring 2005 Name: ______________________________ 1) Write a balanced chemical equation for the following reaction in basic solution: (10 points) Cr +3 (aq) + MnO 2 (s) CrO 4-2 (aq) + Mn +2 (aq) (4H 2 O + Cr +3 CrO 4-2 + 8H + + 3e- ) x2 (2e- + 4H + + MnO 2 Mn +2 + 2H 2 O ) x 3 6e- + 12H + + 3MnO 2 + 8H 2 O + 2Cr +3 2CrO 4- + 16H + + 6e- + 3Mn +2 + 6H 2 O 3MnO 2 + 2H 2 O + 2Cr +3 2CrO 4- + 4H + + 3Mn +2 (in acid) 3MnO 2 + 4OH- + 2Cr +3 2CrO 4- + 2H 2 O + 3Mn +2 (in base) 2) Write a balanced chemical reaction whose H is the H f for gaseous ammonia. (10 pts) 1/2N 2 (g) + 3/2H 2 (g) NH 3 (g) 3) Stainless steel is typically paramagnetic. However by heating type 304 stainless steel to a temperature of 1100.0 C, a phase transition occurs to a diamagnetic phase and if cooled slowly back to room temperature the steel is trapped in the diamagnetic phase at room temperature (pretty neat trick, eh?). It is known that the H f for the paramagnetic...
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- Fall '05