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The chemical equation is a language of chemistry, one that chemists and chemical educators use constantly. Once chemical equations have been introduced in a course of study, it is often assumed that students understand this representational system. But many of the difficulties in learning chemistry are related to chemical equations (1). If students do not understand the language used by the instructor, how can they be expected to understand what is said? In balancing equations, it is important to understand the difference between a coefficient of a formula and a subscript in a formula. The coefficients in a balanced chemical equation can be interpreted both as the relative number of molecules, moles or formula units involved in the reaction. And subscripts on the other hand indicate the relative number of atoms in a chemical formula. Subscripts should never be changed in balancing an equation, because changing subscript changes the identity of the substance. In contrast, changing a coefficient in a formula changes only the amount and not the identity of the substance and hence can be manipulated in balancing chemical equations. Balancing equation go further than word equation. It gives the formula of the reactants and products and shows the relative number of particles of each of the reactant and the products. Notice that the atoms have been reorganized. It is also important to recognize that in a chemical reaction, atoms are neither created nor destroyed. In other words, there must be the same number of each type of atom on the product side and on the reactant side of the arrow. Thus, a chemical equation should obey the law of conservation of mass. Previous studies (2; 3) have shown that students can produce correct answers to various kinds of problems, including those involving chemical reactions, but their understanding of the underlying chemical concepts was lacking. |
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