General Chemistry 145-G (Fall, 2017) Exam-Final (12/13/2017); 120 min, Total Poi
ID: 698221 • Letter: G
Question
General Chemistry 145-G (Fall, 2017) Exam-Final (12/13/2017); 120 min, Total Points 100pts 9. (8 points) at 298K and 1 bar, given the following chemical equations and their respective enthalpy changes: C(graphite)+Ol(g) COle) 2H2(g) + O2(g) 2H2O(1) AH- -393.5 k) Determine the standard enthalpies of formation AHi for CO.(g), H:0() and 10. (6 points) Consider the three electronic transitions in a hydrogen atom shown here, labeled A, B, and C. Which transition is associated with the shortest wavelength of the photon emitted? Calculate its value in nm. 218Explanation / Answer
9.
deltaH0f(CO2) = - 393.5 kJ/mol
deeltaH0f(H2O) = - - 571.6 / 2 = 285.8 kJ/mol
C2H2 (g) + 5/2 O2 (g) ----------> 2 CO2 (g) + H2O (l)
deltaH0r = 2 deltaH0f(CO2) + deltaH0f(H2O) - deltaH0f(C2H2) - (5/2) deltaH0f(O2)
- 1299.6 = 2 ( - 393.5 ) + ( - 285.8 ) - deltaH0f(C2H2) - (5/2) (0 )
deltaH0f(C2H2) = + 226.8 kJ/mol
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