AP Chemistry MIDTERM review C
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Zn + N O 3- + H+ ?Zn2+ + N H 4+ + H 2O Which statement about this reaction is correct? The oxidation number of H changes from +1 to 0 The oxidation number of H changes from +1 to -1 The oxidation number of N changes from +5 to -3 The oxidation number of N changes from +5 to +3 The oxidation number of N changes from +6 to +4 Assign oxidation numbers to each element Zinc goes from 0 to +2 (lost 2 electrons) N goes from +5 to -3 (gained 8 electrons) C 100 0 +5 -2 -3 +1 +1 -2 2H2O2(g) + S(s) ? SO2(g) + 2H2O(g) What is the enthalpy change in the reaction? C 200 Substance ?Hf (kJ/mol) H2O2(g) -150 S(s) 0 SO2(g) -300 H2O(g) -250 -500 kJ -200 kJ 200 kJ 400 kJ 600 kJ [2(-250) + (-300) ] ? [2(-150) + 0] = -500 C 300 CH3CH2OH(g) + ___O2(g) ? ___CO2(g) + ___H2O(g)
