sium permanganate with sulfuric acid and nitric acid with alcohols.

Suspensions of oxidizable particles (e.g., flour, coal dust, magnesium powder, zinc dust, carbon powder, and flowers of sulfur) in the air can constitute a powerful explosive mixture. These materials should be used with adequate ventilation and should not be exposed to ignition sources. Some solid materials, when finely divided, are spontaneously combustible if allowed to dry while exposed to air. These materials include zirconium, titanium, Raney nickel, finely divided lead (such as prepared by pyrolysis of lead tartrate), and catalysts such as activated carbon containing active metals and hydrogen.

Not all explosions result from chemical reactions. A dangerous, physically caused explosion can occur if a hot liquid or a collection of very hot particles comes into sudden contact with a lower-boiling-point material. Sudden boiling eruptions occur when a nucleating agent (e.g., charcoal, ''boiling chips") is added to a liquid heated above its boiling point. Even if the material does not explode directly, the sudden formation of a mass of explosive or flammable vapor can be very dangerous.

The hazards of running a new reaction should be considered especially carefully if the chemical species involved contain functional groups associated with explosions (see Table 3.11) or are unstable near the reaction or work-up temperature, if the reaction is subject to an induction period, or if gases are by-products. Modern analytical techniques (see Chapter 5, section 5.G) can be used to determine reaction exothermicity under suitable conditions.

Even a small sample may be dangerous. Furthermore, the hazard is associated not with the total energy