Ch 100: Fundamentals for ChemistryChemical Equations: What do they tell us?Information Given by the Chemical EquationInterpretation of the Chemical EquationMole and Mass Ratios in Chemical EquationsExampleCh 100: Fundamentals for ChemistryCh 9: Calculations from Chemical ReactionsLecture Notes (Sections 9.1 to 9.5)Chemical Equations: What do they tell us?A properly written chemical equation will provide the following information:1. All reactants & products involved in the reaction2. The physical state of all reactants & products3. The presence of any catalysts involved in the chemical reaction4. The relative quantity of all reactants & productsa. Molecule to molecule ratiosb. Mole to mole ratiosc. Even mass to mass ratios can be determined (with use of molar mass values)Information Given by the Chemical EquationA balanced chemical equation provides the relationship between the relative numbers of reacting molecules and product moleculesExample: The formation of carbon dioxide from carbon monoxide and oxygen gas2 CO + O2 2 CO2In this chemical equation, it is indicated that 2 CO molecules react with every 1 O2 molecule to produce 2 CO2 moleculesAlternative interpretation: there is a 2:1 (numerical) ratio of CO to O2 for this completed reaction, 2 CO:1 O2 :2 CO2Interpretation of the Chemical Equation•Since the information given in a balanced chemical reaction is relative:2 CO + O2 2 CO2the following are alternative interpretations of the chemical equation:a. 200 CO molecules react with 100 O2 molecules to produce 200 CO2 moleculesb. 2 billion CO molecules react with 1 billion O2 molecules to produce 20 billion CO2 moleculesc. 2 moles CO molecules react with 1 mole O2 molecules to produce 2 moles CO2 moleculesd. 12 moles CO molecules react with 6 moles O2 molecules to produce 12 moles CO2 molecules•Note: The coefficients in the balanced chemical equation also shows the molecules and mole ratio of the reactants and products•Since moles can be converted to masses, we can determine the mass ratio of the reactants and products as wellMole and Mass Ratios in Chemical EquationsFor the following chemical equation:2 CO + O2 2 CO2The following mole relations are implied:2 moles CO : 1 mole O2 : 2 moles CO2Note the molar masses of the compounds in this reaction:a. 1 mole of CO = 28.01 gb. 1 mole O2 = 32.00 gc. 1 mole CO2 = 44.01 gThe mass ratio of the compounds in this reaction can be determined using the molar mass values:2(28.01) g CO : 1(32.00) g O2 : 2(44.01) g CO2The mass ratio of the compounds in this reaction are:56.02 g CO : 32.00 g O2 : 88.02 g CO21. Write the balanced equation 2 CO + O2 2 CO22. Use the coefficients to find the mole relationship2 moles CO : 1 mol O2 : 2 moles CO23. Use dimensional analysis to obtain the # of molesa. The # mol of CO:b. The # mol of CO2:ExampleDetermine the Number of Moles of Carbon Monoxide required to react with 3.2 moles Oxygen, and the moles of Carbon Dioxide produced 222 moles CO3.2 moles O x 6.4 moles CO1 mole O� �=� �� �22 222 moles CO3.2 moles O x 6.4 moles CO1 mole O� �=� ��
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