Question

1 ton of TNT can produce 4.6 x 109 J of energy. A chemist wants to know how to obtain this much energy from acetylene (C2H2) and Oxygen (O2). How much acetylene and Oxygen would be required? Provide the name and structure of the "TNT". Reaction between Acetylene and Oxygen: ΔH= -2510 KJ

Answer 1

Ans. Given,

            1 ton of TNT releases 4.6 x 10⁹ J energy = 4.6 x 10⁶ kJ.

TNT (2-methyl-1,3,5-trinitrobenzene)

# Balanced combustion of acetylene-

            2 C₂H₂ + 5 O₂ ------------> 4 CO₂ + 2 H₂O                    ; dH = -2510 kJ

Note: Molar enthalpy of combustion of acetylene is -1255.57 kJ/mol. So, the value “2510 kJ” must be for two moles of acetylene as shown in above reaction.

# So, enthalpy of acetylene combustion = 2510 kJ/ 2 mol acetylene

Now,  

Amount of acetylene required = Energy from 1 ton TNT / enthalpy of acetylene

                                                = 4.6 x 10⁶ kJ / (2510 kJ/ 2 mol acetylene)

                                                = 3.6653 x 10³ mol acetylene.

According to the stoichiometry of balanced reaction, 1 mol acetylene reacts with 5 mol O₂.

So,

            Required moles of O₂ = (5 / 2) x required moles of acetylene

                                                = (5/ 2) x 3.6653 x 10³ mol

                                                = 9.1633 x 10³ mol

# Required mass of acetylene = Required moles x Molar mass

                                                = 3.6653 x 10³ mol x (26.03788 g/ mol)

                                                = 9.8438 x 10⁴ g

                                                = 98.438 kg

Required Mass of O₂ = = 9.1633 x 10³ mol x (31.9988 g/ mol)

                                                = 2.9322 x 10⁵ g

                                                = 293.22 kg