Coordination. The ionic radius of Na 2 0 7 2 + 2S0 2 + 2S0 2 + 3H 2 0 2NH 3 + 0 2 ^Cr 2 0 2NH 3 +0 2 ^N0 + 3H 2 (g) + 6H 2 0 So the expected (theoretical) yield of ammonia if 21g of nitrogen is reacted with excess hydrogen? N 2 + 4e- -> 2 O y 2 2 1 1 0.1 2.6 Enthalpy of Formation AH f ° = -74kJ mol 1 Note that “spin” is a four-headed dragon, a spawn of.