You may improve this article, discuss the issue on the talk page, or create a new article, as appropriate. (January 2015) The history of economic thought deals with different thinkers and theories in the subject that became political economy and economics, from the ancient world to the present day. It encompasses many disparate schools of economic thought.
A pure substance is a substance that cannot be separated by physical means. eg. filtration, evaporation, distillation or chromatography. Examples of pure substances include water, gold, glucose, carbon dioxide, oxygen and hydrogen. A pure substance is made up of one type of particle. The particle that makes up water is H 2 O. The particle that makes up carbon dioxide is CO 2.
Pure Substances and Mixtures â¢ A pure substance is a type of matter that contains only one kind of particle. For example, aluminum, table sugar, and distilled water are pure substances. â¢ A mixture is a type of matter that contains two or more pure substances mixed together. For example, steel, salt water, milk, and air are mixtures. â¢ Mixtures can be solids, liquids, or gases, or even combinations of these.