Posted: May 22nd, 2023
When two or more substances are mechanically combined, it results to a mixture. The constituents of the consequent mixture lack a chemical bond and for this reason, the mixture can separated using suitable physical means. Each component in a mixture retains its chemical attributes. Mixtures can either be homogeneous where the components exhibit uniformity or heterogeneous where the components are easily identifiable. If water is mixed with sugar, a homogeneous mixture is obtained whereby the components can be recovered by evaporation. If iron filings and sulphur powder are mechanically blended, a mixture is obtained. The individual components can be obtained in their pure form using a magnet (Tillery, Enger & Ross, p. 23).
A compound is a chemical entity consisting of two or more chemical elements, which are combined by a chemical process. In a compound, the elements are held together by chemical bonds, which can be ionic, covalent or dative. For example, two hydrogen atoms are covalently linked with an oxygen atom to form a water molecule. A compound exhibits unique properties, physical and chemical, which significantly differ from those of its elements. The elements in a compound are always in a fixed ratio and the arrangement is defined. Therefore, a compound can be represented by a chemical formula, which depicts its exact elemental composition. The elements of a compound can only be separated by chemical means for example, by hydrolysis to break water into hydrogen and oxygen (Ramsden 2001, p. 47).
By mere observation, it is hard to differentiate a pure element from a compound. Therefore, there is obvious necessity to conduct various tests to ascertain the true nature of a substance. Since compounds are composed of elements that are chemically combined, chemical means must be used to differentiate a compound from a pure element. The sample provided should be subjected to a chemical separation process for instance, hydrolysis where the analyst will have means of collecting the various products liberated. These products are then subjected to similar chemical and physical tests. If the outcome is similar for the samples collected, then the initial sample was an element. If the samples collected react differently with the same reactant, then the sample involved was a compound.
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