Hydrazine ($N_2{H}_4$) is used as a rocket propellant. It reacts with oxygen ($O_2$) to produce nitrogen gas ($N_2$) and water vapour ($H_{2}O$) according to the following chemical equation:

$$N_2{H}_4+O_2⟶N_2+2H_{2}O$$

The bonds broken and made during this reaction are as follows:

• Reactants: one mole of hydrazine ($N_2{H}_4$) contains 1 mole of $N-N$ single bonds and 4 moles of $N-H$ single bonds; one mole of oxygen ($O_2$) contains 1 mole of $O=O$ double bonds.
• Products: one mole of nitrogen ($N_2$) contains 1 mole of $N\equiv N$ triple bonds; two moles of water ($H_{2}O$) contain 4 moles of $O-H$ single bonds.

Table 1 shows the bond energies for these bonds.

Table 1