Separating Mixtures
Refinery distillation towers.Copyright 2005 Luigi Chiesa, Wikimedia Commons http://commons.wikimedia.org/wiki/File:Colonne_distillazione.jpg
Students learn how to classify materials as mixtures, elements or compounds and identify the properties of each type. The concept of separation of mixtures is also introduced since nearly every element or compound is found naturally in an impure state such as a mixture of two or more substances, and it is common that chemical engineers use separation techniques to separate mixtures into their individual components. For example, the separation of crude oil into purified hydrocarbons such as natural gas, gasoline, diesel, jet fuel and/or lubricants.
Almost all materials in the universe are found naturally in impure states such as mixtures of two or more substances. In chemistry and chemical engineering, a separation process is commonly used to transform a mixture of substances into two or more distinct materials. The separated products might differ in chemical properties or some physical property, such as size or crystal modification or other separation into different components. One example of separation application is crude oil, which is a mixture of various hydrocarbons. While valuable in this natural form, demand is greater for the various purified hydrocarbons such as natural gases, gasoline, diesel, jet fuel, lubricating oils, asphalt, etc. Chemical plants commonly have from 40% to 70% of both capital and operating costs in separations.[1] Since separations are ubiquitous in chemical plants and petroleum refineries, chemical engineers must be familiar with a variety of separation methods.
After this lesson, students should be able to:
- Define element, mixture and compound.
- Explain the differences between pure substances and mixtures.
- Explain the characteristics of the mixtures.
- Give some examples of elements, mixtures and compounds.
- Define the homogenious and heterogeneous mixtures and give some examples.
- Explain in general how mixtures can be separated.
- Name some separation techniques.
- Explain how chemical engineers apply these separation methods to purify various hydrocarbons such as natural gases, gasoline, diesel, jet fuel, lubricating oils, asphalt, etc., from raw crude oil.