CHY 102 Lecture Notes - Lecture 24: Heat Capacity, Internal Energy, Joule
Document Summary
The reaction of acetylene (c2h2) with h2(g) can produce either ethylene (c2h4), rh = . 175. 7 kj/mol, or ethane (c2h6), rh = 312. 0 kj/mol. The rh for the reaction of ethylene with hydrogen to form ethane is: + 487. 7 kj/mol of c2h4, + 136. 3 kj/mol of c2h4, 136. 3 kj/mol of c2h4, 487. 7 kj/mol of c2h4. Hint: start by writing out the full thermochemical equations (all three) C2h2 (g) + h2 (g) c2h4 (g) rh = -175. 7 kj/mol. We want c2h4 as the reactant, so reverse first rxn. C2h4 (g) c2h2 (g) + h2 (g) rh = +175. 7 kj/mol. C2h2 (g) + 2h2 (g) c2h6 (g) rh = -312. 0 kj/mol. C2h4 (g) + h2 (g) c2h6 (g) rh = -136. 3 kj/mol. Standard enthalpy of formation, fh , is the rh that produces 1 mol of a product and only that product from its elements with all participants in their standard states.
