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Unformatted text preview: Molecular and Chemical Formulas Atoms combine (bond) to form molecules. Each molecule has a chemical formula. The chemical formula indicates which atoms are found in the molecule, and in what proportion they are found. CHEMICAL FORMULA Formula that gives the TOTAL number of elements in a molecule or formula unit. EMPIRICAL FORMULA Chemical formula with the smallest integer subscripts for a given CHEMICAL FORMULA Formula that gives the TOTAL number of elements in a molecule or formula unit. EMPIRICAL FORMULA Chemical formula with the smallest integer subscripts for a given composition. Molecular weight To get the molecular formula, we need more information. Need: molecular weight. Empirical Formula from Analysis How do we determine the empirical formula? Start with mass % of elements (i.e. empirical data) and calculate a formula, or Start with the formula and calculate the mass % elements. How to get empirical formulas PERCENT COMPOSITION % of element = % of element = MOLAR MASS or FORMULA WEIGHT sum of atomic weights The connection between experimental property (mass) and moles: C 8 H 18 8 C 12.01 96.08 18H 1.008 18.14 114.22 (atoms of element)(AW) FW of compound ! 100 100 sample g 100 element of mass ! What is the mass percent of C in CO 2 ?...
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This note was uploaded on 03/31/2008 for the course CHEM 110 taught by Professor Hofmann,brucerob during the Fall '08 term at Pennsylvania State University, University Park.
 Fall '08
 HOFMANN,BRUCEROB
 Atom, Mole

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