ThermochemistryMedium

Question

Diborane is a potential rocket fuel which undergoes combustion according to the following reaction.

B2H6(g) + 3O2(g) → B2O3(s) + 3H2O(g)

From the following data, calculate the enthalpy change for the combustion of diborane.

2B(s) + 3/2 O2(g) → B2O3(s): ΔH = −1273 kJ/mol

H2(g) + ½ O2(g) → H2O(l): ΔH = −286 kJ/mol

H2O(l) → H2O(g): ΔH = 44 kJ/mol

2B(s) + 3H2(g) → B2H6(g): ΔH = 36 kJ/mol

Options

A.−2167 kJ/mol
B.−1478 kJ/mol
C.−2035 kJ/mol
D.−1999 kJ/mol

Solution

From (i) + 3(ii) + 3(iii) – (iv); ΔH = –2035 KJ

Create a free account to view solution

View Solution Free
Topic: Thermochemistry·Practice all Thermochemistry questions

More Thermochemistry Questions

The bond enthalpies of C–C, C=C and C≡C bonds are 348, 610 and 835 kJ/mol, respectively at 298 K and 1 bar. The enthalpy...In a flask, colourless N2O4 is in equilibrium with brown coloured NO2. At equilibrium, when the flask is heated at 373 K...2MnO4 – + 16H+ + 10Cl– → 2Mn2+ + 5Cl2(g) + 8H2OThe above reaction is endothermic and hence, the actual temperature of th...The molar heat capacities of A, B and C are in the ratio 1:2:3. The enthalpy change for the reaction A + B → C at temper...The following are various ΔH values (kJ per mol), ΔfH (NaCl) = – 411.2; ΔfH (Na, g) = 107.3; ΔfH (Cl, g) = 121.7; ΔiH (N...