Question

Trinitroglycerin, C3H5N3O9 (usually referred to simply as nitroglycerin), has been widely used as an explosive. Alfred Nobel used it to make dynamite in 1866. Rather surprisingly, it also is used as a medication, to relieve angina (chest pains resulting from partially blocked arteries to the heart) by dilating the blood vessels. At 1 atm pressure and 25 °C, the enthalpy of decomposition of trinitroglycerin to form nitrogen gas, carbon dioxide gas, liquid water, and oxygen gas is –1541.4 kJ/mol.

One common form of trinitroglycerin melts at about 3 °C. From this information

1. and the formula for the substance, would you expect it to be a molecular or ionic

   compound? Explain.

2. Describe the various conversions of forms of energy when trinitroglycerin is used

   as an explosive to break rockfaces in highway construction.

Answer 1

Solution:

Trinitroglycerine (TNT) is a covalent compound because it has a nitro-group (NO2) attached with CH2 group. Again lower melting point also indicates its covalent bonding. The decomposition of nitroglycerine produces large amount of heat which is responsible for its explosive nature.

Explosion of TNT is a process of converting chemical energy into heat energy. Thus, on explosion the energy of TNT is converted into thermal energy.