Question

Which of the following correctly describes the decomposition of aqueous NaNO3?
Given:
NaNO3(aq):ΔH= –477 kJ

The molar enthalpy is –447 kJ and the reaction is exothermic.

The molar enthalpy is 447 kJ and the reaction is exothermic.

The molar enthalpy is –447 kJ and the reaction is endothermic.

The molar enthalpy is 447 kJ and the reaction is endothermic.

Answer 1

I would go for the last one, because decomposition reaction need more energy input than output and when this is the case, a reaction is given to be endothermic and when energy is given in, the value is positive.

Answer 2

I agree with @hoslos

Decomposition breaks bonds, which is a endothermic reaction. If it's endothermic and absorbing heat, the enthalpy must be positive.