Ask a Teacher

Search



1)when thermal cracking is happen? 2) What are the oxides likely to be formed when hydrocarbons burn in air? 3) what is called wash?
1.
       i) Thermal cracking is a process in which hydrocarbons such as crude oil are subjected to high heat and temperature to break the molecular bonds and reduce the molecular weight of the substance being cracked. This process is used to extract usable components, known as fractions, which are released during the cracking process. It is one among several cracking methods used in the petroleum industry to process crude oil and other petroleum products for commercial use.

      ii)Combustion of fuels

Complete combustion

Fuels burn when they react with oxygen in the air. If there is plenty of air, complete combustion happens. Coal is mostly carbon. During complete combustion, carbon is oxidized to carbon dioxide:

carbon + oxygen ? carbon dioxide

Carbon dioxide is a greenhouse gas. Increasing concentrations of it in the atmosphere contribute to global warming.

Hydrocarbon fuels contain carbon and hydrogen. During combustion, hydrogen is oxidized to water (remember that water, H2O, is an oxide of hydrogen). In general:

hydrocarbon + oxygen ? carbon dioxide + water


Incomplete combustion

If there is insufficient air for complete combustion, incomplete combustion (also called partial combustion) happens. Hydrogen is still oxidized to water, but carbon monoxide forms instead of carbon dioxide. Carbon monoxide is a toxic gas, so adequate ventilation is important when burning fuels.

Solid particles (particulates) are also released. These contain carbon and are seen as soot or smoke. Particulates cause global dimming. They reduce the amount of sunlight reaching the Earth’s surface.


iii) wash -  in what aspect?


comments powered by Disqus