008351molessn relativenumberofsnatoms 1000

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Unformatted text preview: f ato ms in a substance · Two important type of formulas will be discussed and compared: MOLECULAR FORMULAS EMPIRICAL FORMULAS (Simplest Formulas) can be written for both molecular and ionic compounds can be written for molecular compounds only ­ indicate the number of atoms of each kind in a molecule ­ are multiples of empirical formulas indicate the smallest whole number ratio between the atoms or ions of a substance (smallest whole number subscripts) Multiplier H2O2 (hydrogen peroxide) H2O C2H2 (acetylene) C6H6 (benzene) C6H12O6 (glucose) C6H12 (cyclohexane) C6H4Cl2 Does not exist for an Ionic Compound Does not exist for an ionic compound 9 HO H2O CH CH CH2O CH2 C3H2Cl NaCl SnO2 2 1 2 6 6 6 2 ­­ ­­ Chemistry 101 Chapter 3 Calculating the Empirical (Simplest Formula) Information Required: ­ Percentage Composition by Mass, or ­ Composition by weight Example: Tin (Sn) reacts with oxygen (O) to form an oxide of tin (SnaOb), which contains 0.9913 g Sn and 0.2729 g O. What is the Empirical Formula of the oxide ? (that is: a = ? b = ?) Step 1: MASS MOLE 1 mole Sn ? moles Sn = 0.9913 g Sn x ¾¾¾¾¾ = 0.008351 moles Sn atoms 118.71 g Sn 1 mole O ? moles O = 0.2729 g O x ¾¾¾¾¾ = 0.01706 moles O atoms 16.00 g O Step 2: DIVIDE BY SMALL 0.01706 moles O Relative number of O atoms = ¾¾¾¾¾¾¾¾ = 2.043 0.008351 moles Sn 0.008351 moles Sn Relative number of Sn atom...
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