Which reaction is exothermic? -CH4 + 2O2 Right arrow. CO2 + 2H2O + 891 kJ
-NH4NO3 + H2O + 25 kJ Right arrow. NH4+(aq) + NO3-(aq)
-2H2O + 286 kJ Right arrow. 2H2 + O2
-N2 + O2 + 181 kJ Right arrow. 2NO

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"

the population of unionid mussels in the hudson river decreased after zebra mussels were introduced. zebra mussels, a nonnative species, competed with the unionid mussels for food. the zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. the unionid mussel population decreased due to a lack of food.

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