Question

Which reactions are endothermic? (Select all that apply.)

A. H2(g) + ½O2(g) H2O(aq), H = -57.83 kcal/mole
B. ½ N2(g) + ½O2(g) NO(g), H = +21.6 kcal/mole
C. ½N2(g) + O2(g) + 8.1 kcal NO2(g)
D. ½N2(g) + 3/2 H2(g) NH3(g) + 11.0 kcal/mole
E. NH3(g) ½N2(g) + 3/2 H2(g), H = +11.0 kcal/mole

Answer 1

Reactions B,C,D and E are endothermic since the enthalpy change for each is positive. When endothermic reactions occur, they absorb energy from the environment thus the overall energy change becomes positive( they are all preceded by a plus sighn, +)

Answer 2

Answer:

NH 3 (g)  ½N 2 (g) + 3/2 H 2 (g),  H = +22 kcal/mole

½N 2 (g) + O 2 (g) + 8.1 kcal  NO 2 (g)

½ N 2 (g) + ½O 2 (g)  NO(g),  H = +21.6 kcal/mole

Explanation:

i got them right