Question

Among the substances that react with oxygen and that have been considered as potential rocket fuels are diborane [B₂H₆, produces B₂O₃(s) and H₂O(g)], methane [CH₄, produces CO₂(g) and H₂O(g)], and hydrazine [N₂H₄, produces N₂(g) and H₂O(g)]. On the basis of the heat released by 1.00 g of each substance in its reaction with oxygen, which of these compounds offers the best possibility as a rocket fuel?

ΔH°f (B₂H₆) = -36.4Kj/mol
ΔΗ°f (H₂O) = -241.82 Kj/mol
ΔΗ°f (B₂O₃) = -1273.5 Kj/mol
ΔΗ°f (CO₂) = -393.51 Kj/mol
ΔΗ°f (CH₄) = -74.6 Kj/mol
ΔΗ°f (N₂H₄) = 50.63 Kj/mol

Answer 1

Diborane (B₂H₆) offers the best possibility as a rocket fuel as it releases the most heat.

Step-by-step explanation:

To determine which compound offers the best possibility as a rocket fuel, we need to compare the heat released by 1.00 g of each substance in its reaction with oxygen. We can calculate this by subtracting the heat of formation of the products from the heat of formation of the reactant. Let's calculate the heat released for each compound:

For diborane (B₂H₆): 1.00 g * (-36.4 kJ/mol) / (2 g/mol) = -18.2 kJ

For methane (CH₄): 1.00 g * (-74.6 kJ/mol) / (16 g/mol) = -4.66 kJ

For hydrazine (N₂H₄): 1.00 g * (50.63 kJ/mol) / (32 g/mol) = 1.58 kJ

Based on these calculations, diborane (B₂H₆) offers the best possibility as a rocket fuel as it releases the most heat.