Gas Products in Explosion of Liquid Explosives

There are other materials, whose reactions are rapid and release a lot of energy/ heat at the same time. However, the reactions do not generate gas productions. These materials are not explosives. Take thermite reaction as an example, 

The heat released in this reaction is enough to raise the temperature of products at 3,000 °C while Fe and AI2O3 are liquids now. No gas is produced in this reaction, and it is nonexplosive. 

In certain conditions, rapid and exothermic reactions without gas production also lead to explosion. E.g., reactions of well-grounded thermite reactants in the air make the nearby air heated and expand, and then explode. This explosion comes from the heated air, not the reaction of thermites. Sometimes the amount of gases reduces rather than increase, especially the explosive reaction of gas reactants. The explosion of detonation gas is listed below. 

In above reaction, 1/3 amount of gases is cut off. The rapidity and exothermicity make up the reduction of gas amount. The volume of gases increases rapidly under high temperature. If the volume is maintained, the pressure reaches more than 10 atm within an extreme short time. This is the key feature of detonation gases. 

In simimary, exothermicity, rapidity, and gas productions are key features of explosive reactions. Exothermicity of reactions supplies the initiating energy for explosion. Rapidity is the must condition which helps to confine the limited energy into small space, while produced gases are media of energy conversion. Explosion power has close relationship with exothermicity, rapidity, and gas productions. Exothermicity helps heat explosive to a relative high temperature, which increases the reaction speed and makes the reaction reach rapidity. In addition, the released energy dramatically increases the temperature and promotes the conversion of reaction products into gas state. 

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