# Empirical and Molecular Formulas_Balancing Eqns for Individual Work.pdf

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Page 1Empirical and Molecular Formulas, Balancing EquationsTextbook Reference: Chemistry: Atoms First 2e, Sections 6.2 and 7.1ObjectivesCalculate percentage composition of a compound from the chemical formula.Calculate the Empirical Formula from experimental data.Distinguish between Empirical Formula and Molecular Formula.Determine a Molecular Formula given molecular mass and empirical formula for a compound.Model 1:Percentage Composition of H2O2(hydrogen peroxide)To calculate the Percent Composition (or mass percent) of each element in a compound, you must determine theatomic mass of each element and the molecular mass of the compound. You know the atomic masses of the atomsfrom the Periodic Table so can calculate the molecular mass for H2O2:2 (1.01 amu) + 2 (16.00 amu) = 34.02 amuNow you can calculate the percentage composition of each atom in hydrogen peroxide.Hydrogen:! (\$.&\$ ’())+,.&! ’()࠵? 100% = 5.94%Oxygen:! (\$-.&& ’())+,.&! ’()࠵? 100% = 94.06%Model 1 Exercises1.Phosphoric acid (H3PO4) is a colorless, syrupy liquid used in detergents, fertilizers, toothpastes, and incarbonated beverages for a “tangy” flavor.Calculate the percent composition by mass of H, P, and O in thiscompound.2.An 11.5 gram sample of ethanol contains 6.00 g of carbon and 1.51 g of hydrogen.The remainder must beoxygen, as ethanol only contains these three elements.What is the percent composition of each element inthis compound?

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