Observed in Illinois on the first Monday of March every year, the holiday ostensibly honors Polish-born Revolutionary War cavalry officer Casimir Pulaski, though for most school kids with a four-day week, itâs probably just another sweet, sweet sleep-in day.
Yes, in chemistry a pure substance means either an element or a compound. Thus, hydrogen, oxygen, sodium, iron, copper etc. are pure substances; and so are compounds such as water, sugar, ammonia, sodium chloride, methane, ethanol etc. A compound is composed of two or more elements combined in a fixed ratio by mass. Like an element, a compound also has a distinct chemical identity. A mixture is not a pure substance as it is a collection of two or more elements/compounds in varying ratio. Air, sea water, gasoline, vegetable oils, steel etc. are mixtures.
Publishing as Benjamin Cummings. 3. A pure substance is classified as. â¢ matter with a specific and constant composition. â¢ an element when composed of one type of atom. â¢ a compound when composed of two or more. elements combined in a definite ratio. Pure Substances.