Chapter 5, Problem 5.43QE

Another reaction that is used to propel rockets is

${\text{N}}_{\text{2}}{\text{O}}_{\text{4}}\left(\mathcal{l}\right)+2{\text{N}}_{\text{2}}{\text{H}}_{\text{4}}\left(\mathcal{l}\right)\to 3{\text{N}}_{\text{2}}\left(\text{g}\right)+4{\text{H}}_{\text{2}}\text{O}\left(\text{g}\right)$

This reaction has the advantage that neither product is toxic, so no dangerous pollution is released. When the reaction consumes 10.0 g liquid N₂O₄, it releases 124 kJ of heat.

1. (a) Is the sign of the enthalpy change positive or negative?
2. (b) What is the value of ΔH for the chemical equation if it is understood to be written in molar quantities?