PPT-Lesson 27 Empirical Formula

Objectives          The student will determine an empirical or simplest formula from percentage composition data   PA Science and Technology Standards 3410A 3412A PA Mathematics Standards 2211A 2311C 2411E 2511A. Chemical Formula Relationships. Number of Atoms in a Formula. In writing the formula of a substance, subscript numbers are used to indicate the number of atoms or groups of atoms of each element in the formula unit.. . vs. . Empirical Formula. Different compounds can have the . same. empirical formula. but . different. molecular formulas. .. Empirical . Formula is a . reduced. . form of Molecular formula . Molecular Formula and Empirical Formula. Molecular Formulas. Let’s use those mole conversions!. Empirical formula . tells you the lowest ratio of atoms within a molecule. Molecular formula . tells you the actual ratio of atoms within a molecule. You should know this for the quiz!. Empirical and Molecular Formulae. Empirical Formula. If needed, change % to g.. Do . a molar conversion to change from . g. mol. Divide each of these numbers by the smallest number. Chemistry GT 3/20/15. Drill. Calculate the percent composition of Na. 2. SO. 4. .. HW: Molecular Formula WS (pg. 4). MM. =142.05 . g. /mol. 32.37% Na, 22.58% S, 45.05% O. Chem. Joke of the Day. The photon checked into a hotel. What did it say when the bellhop asked for its bag?. Empirical & Molecular Formula Notes. Drill. Calculate the percent composition of Na. 2. SO. 4. .. HW:. Finish pg. 3 (Empirical Formulas). MM=142.05 . g. /mol. 32.37% Na, 22.58% S, 45.05% O. Objectives. Represents the . actual. number of . atoms. of each . element. in . compound. Not necessary for . ionic compounds. Necessary for . covalent compounds. The molecular formula for water is . H. 2. O. Formula from Exp. erimental D. at. a. Analysis of a Compounds Constituent Elements. The mass of elements that make up a compound can be used to determine the compounds chemical formula.. When determining a compounds empirical formula from mass data:. The Mole. Chemist’s counting number. amount. of a substance . 1 mole is equal to 6.022 x 10. 23. atoms or particles or molecules (Avogadro’s number). There are always 6.022 x 10. 23 . particles in . Due at end of Period. The compound . benzamide. has the following percent composition. What is the empirical formula? . C . = 69.40 % H= 5.825 % O = 13.21 % N= 11.57 % . 2. A . component of protein called serine has an approximate . Lowest whole # ratio . H. 2. O. 2. (hydrogen peroxide) is it a empirical Formula?. No, you can reduce it to HO . . H. 2. O. 2 . is the molecular formula. Molecular formula shows the way the molecule is actually found in nature.. Determining Molecular Formulas. Calculate the molecular formula of a compound whose molar mass is 60.0 g/mol and has an empirical formula of CH4N.. What you need:. Empirical Formula. Molar Mass. Calculate the molar mass of the empirical formula. Percent Composition. Breaks down the amount of an element in a compound by percentage. Total mass of element / total mass of compound. Result will always be a decimal. Multiply by 100 to get the final percentage. Percent Composition. ~percent by mass of atoms present in a compound. = (mass of atom). . (total molar mass) x 100. water is . 88.81 . % Oxygen and . 11.19 . % Hydrogen. O- 16.00/18.016 x 100 = . 88.81 .