Which of the following reactions is endothermic? h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal ½n2(g) + o2(g) + 8.1 kcal → no2(g) ½n2(g) + 3/2h2(g) → nh3(g) + 11.0 kcal c(diamond) + o2(g) → co2, δh = -94.50 kcal

the reactions: 1/2n2(g)+ o2(g) ⇒ no2(g) +8.1kcal and 1/2n2+3/2h2(g)⇒ nh3(g)+11.0kcal are both endothermic, that is, they react by gaining energy thus the positive enthalpy notation.

a pan containing water is placed in a positio n where it is exposed to a 10 mile per hour wind. the pan contains a uniform depth of 1.27 cm of water, is quite wide, and has a length of 2.44 m in the wind direction. the water in the pan is at a constant temperature of 15.5 °c.