Fire Variables

We saw that fire is the result of a chemical reaction between two gases, typically oxygen and a fuel gas. The fuel gas is created by heat. In other words, with heat providing the necessary energy, atoms in one gaseous compound break their bonds with each other and recombine with available oxygen atoms in the air to form new compounds plus lots more heat.

The most flammable compounds contain carbon and hydrogen, which recombine with oxygen relatively easily to form carbon dioxide, water and other gases.

Different flammable fuels catch fire at different temperatures. It takes a certain amount of heat energy to change any particular material into a gas.

The fuel’s size also affects how easily it will catch fire. A larger fuel, such as a thick tree, can absorb a lot of heat, so it takes a lot more energy to raise any particular piece to the ignition temperature. A toothpick catches fire more easily because it heats up very quickly.

A fuel’s heat production depends on how much energy the gases release in the combustion reaction and how quickly the fuel burns. Both factors largely depend on the fuel’s composition. Some compounds react with oxygen in such a way that there is a lot of “extra heat energy” left over. Others emit a smaller amount of energy. Similarly, the fuel’s reaction with oxygen may happen very quickly, or it may happen more slowly.

The fuel’s shape also affects burning speed. Thin pieces of fuel burn more quickly than larger ones. For example, you could burn up a pile of wood splinters or paper much more quickly than you could a block of wood with the same mass, because splinters and paper have a much greater surface area.

A fire from a fast-burning fuel that produces a lot of heat will inflict a different sort of damage than a slow-burning, low-heat fire.

Найдите в тексте (задание № 10) и выпишите английские эквиваленты к данным словосочетаниям.

1. горючий газ

2. создавать

3. тепло

4. разрушать (молекулярные) связи

5. свободные атомы кислорода

6. легковоспламеняющиеся соединения

7. вновь соединяться с кислородом

8. углекислый газ

9. определенное количество тепловой энергии

10. загораться