Calculations From Chemical Equations Chapter 9Chapter Outline9.1 A Short ReviewSlide 4Slide 5Slide 6Slide 7Slide 8Slide 99.2 Introduction to StoichiometrySlide 11ExamplesSlide 13Slide 14Slide 15Slide 16Step 1 Determine the number of moles of starting substance.Slide 18Step 2 Determine the mole ratio of the desired substance to the starting substance.Slide 20Slide 21Step 3. Calculate the desired substance in the units specified in the problem.Slide 23Slide 24Slide 259.3 Mole-Mole CalculationsPhosphoric AcidSlide 28Slide 299.4 Mole-Mass CalculationsSlide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 379.5 Mass-Mass CalculationsSlide 39Slide 40Slide 41Slide 429.6 Limiting-Reactant and Yield CalculationsLimiting ReactantSlide 45Slide 46Slide 47Steps Used to Determine the Limiting ReactantSlide 49Slide 50Slide 51Slide 52Slide 53Slide 54Reaction YieldThe quantities of products calculated from equations represent the maximum yield (100%) of product according to the reaction represented by the equation.Many reactions fail to give a 100% yield of product.Slide 58Slide 59Slide 60Slide 61Slide 621Calculations FromChemical Equations Chapter 9 Calculations FromChemical Equations Chapter 9 Hein and Arena Eugene Passer Chemistry Department Bronx Community College© John Wiley and Sons, IncVersion 2.012th Edition2Chapter Outline9.1 A Short Review 9.2 Introduction to Stoichiometry9.3 Mole-Mole Calculations9.4 Mole-Mass Calculations9.5 Mass-Mass Calculations9.6 Limiting-Reactant and Yield Calculations39.19.1A Short ReviewA Short Review4•The molar mass of an atom of an element is its atomic mass in grams.•It contains 6.022 x 1023 atoms (Avogadro’s number) of the element.5The molar mass of an element or compound is the sum of the atomic masses of all its atoms.6grams of a substancemolar mass = number of moles of the substancegrams of a monoatomic element molar mass = number of moles of the element23number of molecules number of moles = 6.022 x 10 molecules/mole7Avogadro’s Number of Particles6.022 x 1023 ParticlesMolar Mass1 MOLE81 mole = 6.022 x 1023 molecules1 mole = 6.022 x 1023 atoms1 mole = 6.022 x 1023 ions922Al + Fe2O3 Fe + Al2O3•For calculations of mole-mass-volume relationships:–The chemical equation must be balanced. 2 mol 2 mol1 mol 1 molThe equation is balanced.–The coefficient in front of a formula represents the number of moles of the reactant or product.109.29.2Introduction to StoichiometryIntroduction to Stoichiometry11•Stoichiometry: The area of chemistry that deals with the quantitative relationships between reactants and products.•Mole Ratio: a ratio between the moles of any two substances involved in a chemical reaction.–The coefficients used in mole ratio expressions are derived from the coefficients used in the balanced equation.12ExamplesExamplesExamplesExamples13223 m1 molol HNN2 + 3H2 2NH31 mol 2 mol3 mol141 mol 2 mol3 molN2 + 3H2 2NH3232 mo3 mol Hl NH15•The mole ratio is used to convert the number of moles of one substance to the corresponding number of moles of another substance in a stoichiometry problem.•The mole ratio is used in the solution of every type of stoichiometry problem.16The Mole Ratio Method1. Convert the quantity of starting substance to moles (if it is not already in moles)2. Convert the moles of starting substance to moles of desired substance.3. Convert the moles of desired substance to the units specified in the problem.17Identify the starting substance from the data given in the problem statement. Convert the quantity of the starting substance to moles, if it is not already in moles.1 molemoles = grams molar mass� �� �� �Step 1 Determine the number of moles of starting substance.181 mole NaClmoles NaCl = 292.15 grams NaCl = 5.0000 moles NaCl58.443 g NaCl� �� �� �1 molemoles = grams molar mass� �� �� �How many moles of NaCl are present in 292.215 grams of NaCl? The molar mass of NaCl =58.443 g.19The number of moles of each substance in the balanced equation is indicated by the coefficient in front of each substance. Use these coefficients to set up the mole ratio.moles of desired substance in the equationmole ratio = moles of starting substance in the equationStep 2 Determine the mole ratio of the desired substance to the starting substance.20moles of desired substance in the equationmoles of desired substance = moles of starting substance moles of starting substance in the equation� �� �� �� �� �� �Multiply the number of moles of starting substance (from Step 1) by the mole ratio to obtain the number of moles of desired substance.21moles of desired substance in the equationmoles of desired substance = moles of starting substance moles of starting substance in the equation� �� �� �In the following reaction, how many moles of PbCl2 are formed if 5.000 moles of NaCl react?2NaCl(aq) + Pb(NO3)2(aq) PbCl2(s) + 2NaNO3(aq) 5.000 moles NaCl 2moles of PbCl =22.500 mol PbCl21 mol PbCl2 mol NaCl� �=� �� �22Step 3. Calculate the desired substance in the units specified in the problem.•If the answer is to be in moles, the calculation is complete•If units other than moles are wanted, multiply the moles of the desired substance (from Step 2) by the appropriate factor to convert moles to the units required.23Step 3. Calculate the desired substance in the units specified in the problem.molar mass1. To calculate : grams =gr moles x 1 moamsl� �� �� �22 2218.02 g H O90.10 grams H O = 5.000 mol H O 1 mol H O� �� �� �24236.022 x 10 atoms2. To calculate : atoms = moles 1 moatomsl� �� �� �23246.022 x 10 Na atoms3.011 x 10 Na atoms = 5.000 moles Na atoms 1 mol Na atoms� �� �� �Step 3. Calculate the desired substance in the units specified in the problem.25236.022 x 10 molecules3. To calculate : molecules = mol moles x 1 molecules� �� �� �232422 226.022 x 10 H O molecules3.011 x 10 molecules H O = 5.000 moles H O 1 mol H O� �� �� �Step 3. Calculate the desired substance in the units specified in the problem.269.39.3Mole-Mole CalculationsMole-Mole Calculations27Phosphoric Acid•Phosphoric acid (H3PO4) is one of the most widely produced industrial chemicals in the world.•Most of the world’s phosphoric acid
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