Section Five Stoichiometric Calculations The Workhorse of the
![Section Five Stoichiometric Calculations: The Workhorse of the Analyst Section Five Stoichiometric Calculations: The Workhorse of the Analyst](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-1.jpg)
![Review of Fundamentals • Atomic, Molecular, and Formula Weights • Moles: 1 mole = Review of Fundamentals • Atomic, Molecular, and Formula Weights • Moles: 1 mole =](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-2.jpg)
![How Do We Express Concentrations of Solutions? • • Molarity (M)= moles/liter or mmoles/m. How Do We Express Concentrations of Solutions? • • Molarity (M)= moles/liter or mmoles/m.](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-3.jpg)
![In normality calculations, the number of equivalents is the number of moles times the In normality calculations, the number of equivalents is the number of moles times the](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-4.jpg)
![Density Calculations How do we convert to Molarity • • Density = mass solute Density Calculations How do we convert to Molarity • • Density = mass solute](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-5.jpg)
![Analytical and Equilibrium Concentrations • They are not the same! • Analytical Molarity, Cx Analytical and Equilibrium Concentrations • They are not the same! • Analytical Molarity, Cx](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-6.jpg)
![Dilutions Preparing the Right Concentration • The millimoles taken for dilution will be the Dilutions Preparing the Right Concentration • The millimoles taken for dilution will be the](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-7.jpg)
![Expression of Analytical Results So Many Ways • • • Solid Samples: %(wt/wt) = Expression of Analytical Results So Many Ways • • • Solid Samples: %(wt/wt) =](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-8.jpg)
![Expression of Analytical Results So Many Ways • • • Liquid Samples %(wt/vol) = Expression of Analytical Results So Many Ways • • • Liquid Samples %(wt/vol) =](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-9.jpg)
![The units ppm or ppb are used to express trace concentrations. These are weigh The units ppm or ppb are used to express trace concentrations. These are weigh](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-10.jpg)
![The equivalents (based on charge) of cations and anions are equal. ©Gary Christian, Analytical The equivalents (based on charge) of cations and anions are equal. ©Gary Christian, Analytical](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-11.jpg)
![Reporting Concentrations as Different Chemical Species • We may express results in any form Reporting Concentrations as Different Chemical Species • We may express results in any form](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-12.jpg)
![Volumetric Analysis - Principles • “Titrimetry” – determination of analyte by reaction with measured Volumetric Analysis - Principles • “Titrimetry” – determination of analyte by reaction with measured](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-13.jpg)
![Volumetric Analysis - Principles How Do We Make Stoichiometric Calculations? • 1. 2. 3. Volumetric Analysis - Principles How Do We Make Stoichiometric Calculations? • 1. 2. 3.](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-14.jpg)
![Volumetric Analysis - Principles Standard Solutions • “Primary Standard “ – – highly purified Volumetric Analysis - Principles Standard Solutions • “Primary Standard “ – – highly purified](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-15.jpg)
![Volumetric Analysis - Principles Standard Solutions • “Secondary Standard” – do not meet requirements Volumetric Analysis - Principles Standard Solutions • “Secondary Standard” – do not meet requirements](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-16.jpg)
![Volumetric Analysis - Principles Examples of Standard Materials • • • Primary Potassium Acid Volumetric Analysis - Principles Examples of Standard Materials • • • Primary Potassium Acid](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-17.jpg)
![Volumetric Analysis-Principles • Standardization – involves establishing the concentration of a “standard solution” • Volumetric Analysis-Principles • Standardization – involves establishing the concentration of a “standard solution” •](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-18.jpg)
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![Volumetric Analysis - Principles • • Acid – Base HA + B BH+ + Volumetric Analysis - Principles • • Acid – Base HA + B BH+ +](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-20.jpg)
![Volumetric Analysis - Principles • Dilutions • Vc x C c = Vd x Volumetric Analysis - Principles • Dilutions • Vc x C c = Vd x](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-21.jpg)
- Slides: 21
![Section Five Stoichiometric Calculations The Workhorse of the Analyst Section Five Stoichiometric Calculations: The Workhorse of the Analyst](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-1.jpg)
Section Five Stoichiometric Calculations: The Workhorse of the Analyst
![Review of Fundamentals Atomic Molecular and Formula Weights Moles 1 mole Review of Fundamentals • Atomic, Molecular, and Formula Weights • Moles: 1 mole =](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-2.jpg)
Review of Fundamentals • Atomic, Molecular, and Formula Weights • Moles: 1 mole = 6. 022 x 1023 (atoms, molecules or formula units)
![How Do We Express Concentrations of Solutions Molarity M molesliter or mmolesm How Do We Express Concentrations of Solutions? • • Molarity (M)= moles/liter or mmoles/m.](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-3.jpg)
How Do We Express Concentrations of Solutions? • • Molarity (M)= moles/liter or mmoles/m. L Normality(N) = equivalence/liter or meq/m. L Formality(F)= is identical to molarity Molality(m) = moles/1000 g solvent
![In normality calculations the number of equivalents is the number of moles times the In normality calculations, the number of equivalents is the number of moles times the](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-4.jpg)
In normality calculations, the number of equivalents is the number of moles times the number of reacting units per molecule or atom. ©Gary Christian, Analytical Chemistry, 6 th Ed. (Wiley)
![Density Calculations How do we convert to Molarity Density mass solute Density Calculations How do we convert to Molarity • • Density = mass solute](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-5.jpg)
Density Calculations How do we convert to Molarity • • Density = mass solute /unit volume Specific Gravity = Dsolute/DH 20 DH 2 O = 1. 00000 g/m. L @ 4 o. C DH 2 O = 0. 99821 g/m. L @ 20 o. C
![Analytical and Equilibrium Concentrations They are not the same Analytical Molarity Cx Analytical and Equilibrium Concentrations • They are not the same! • Analytical Molarity, Cx](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-6.jpg)
Analytical and Equilibrium Concentrations • They are not the same! • Analytical Molarity, Cx = sum of all species of the substance in solution • Equilibrium Molarity, [X] = concentration of a given dissolved form of the substance
![Dilutions Preparing the Right Concentration The millimoles taken for dilution will be the Dilutions Preparing the Right Concentration • The millimoles taken for dilution will be the](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-7.jpg)
Dilutions Preparing the Right Concentration • The millimoles taken for dilution will be the same as the millimoles in the diluted solution. • Mstockx m. Lstock = Mdiluted x m. Ldiluted
![Expression of Analytical Results So Many Ways Solid Samples wtwt Expression of Analytical Results So Many Ways • • • Solid Samples: %(wt/wt) =](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-8.jpg)
Expression of Analytical Results So Many Ways • • • Solid Samples: %(wt/wt) = (wt analyte/wt sample)x 102 % pt(wt/wt) = (wt analyte/wt sample)x 103 ppt ppm(wt/wt) = (wt analyte/wt sample)x 106 ppm ppb(wt/wt) = (wt analyte/wt sample)x 109 ppb
![Expression of Analytical Results So Many Ways Liquid Samples wtvol Expression of Analytical Results So Many Ways • • • Liquid Samples %(wt/vol) =](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-9.jpg)
Expression of Analytical Results So Many Ways • • • Liquid Samples %(wt/vol) = (wt analyte/vol sample m. L)x 102 % pt(wt/vol) = (wt analyte/vol sample m. L)x 103 ppt ppm(wt/vol) = (wt analyte/vol sample m. L)x 106 ppm ppb(wt/vol) = (wt analyte/vol sample, m. L)x 109 ppb Liquid Analyte %(vol/vol) = (vol analyte/vol sample m. L)x 102 % pt(vol/vol) = (vol analyte/vol sample m. L)x 103 ppt ppm(vol/vol) = (vol analyte/vol sample m. L)x 106 ppm ppb(vol/vol) = (vol analyte/vol sample, m. L)x 109 ppb
![The units ppm or ppb are used to express trace concentrations These are weigh The units ppm or ppb are used to express trace concentrations. These are weigh](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-10.jpg)
The units ppm or ppb are used to express trace concentrations. These are weigh or volume based, rather than mole based. ©Gary Christian, Analytical Chemistry, 6 th Ed. (Wiley)
![The equivalents based on charge of cations and anions are equal Gary Christian Analytical The equivalents (based on charge) of cations and anions are equal. ©Gary Christian, Analytical](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-11.jpg)
The equivalents (based on charge) of cations and anions are equal. ©Gary Christian, Analytical Chemistry, 6 th Ed. (Wiley)
![Reporting Concentrations as Different Chemical Species We may express results in any form Reporting Concentrations as Different Chemical Species • We may express results in any form](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-12.jpg)
Reporting Concentrations as Different Chemical Species • We may express results in any form of the analyte. • Example: • Water Hardness due to calcium ion is expressed as ppm Ca. CO 3. • Chloride present in Ag. Cl derived from a salt mixture of Na. Cl and KCl.
![Volumetric Analysis Principles Titrimetry determination of analyte by reaction with measured Volumetric Analysis - Principles • “Titrimetry” – determination of analyte by reaction with measured](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-13.jpg)
Volumetric Analysis - Principles • “Titrimetry” – determination of analyte by reaction with measured amount of standard reagent • “Standard Solution” (titrant) – reagent of known concentration • “Titration” – slow addition of titrant to analyte solution from a volumetric vessel (buret) • “Equivalence Point” – reached when amount of added titrant is chemically equivalent to amount of analyte present in the sample. • “End Point” – the occurrence of an observable physical change indicating that the equivalence point is reached. Might differ from Eq. Pt. !
![Volumetric Analysis Principles How Do We Make Stoichiometric Calculations 1 2 3 Volumetric Analysis - Principles How Do We Make Stoichiometric Calculations? • 1. 2. 3.](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-14.jpg)
Volumetric Analysis - Principles How Do We Make Stoichiometric Calculations? • 1. 2. 3. 4. Titration- What are the requirements? Reaction must be stoichiometric Reaction should be rapid No side reactions Marked change in some property of the solution when reaction is complete 5. Equivalence point 6. Reaction should be quantitative
![Volumetric Analysis Principles Standard Solutions Primary Standard highly purified Volumetric Analysis - Principles Standard Solutions • “Primary Standard “ – – highly purified](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-15.jpg)
Volumetric Analysis - Principles Standard Solutions • “Primary Standard “ – – highly purified compound used as a reference material in titrimetry • • Properties: High purity Stable in air Independent of relative humidity Readily available Reasonable solubility Large formula weight
![Volumetric Analysis Principles Standard Solutions Secondary Standard do not meet requirements Volumetric Analysis - Principles Standard Solutions • “Secondary Standard” – do not meet requirements](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-16.jpg)
Volumetric Analysis - Principles Standard Solutions • “Secondary Standard” – do not meet requirements for a primary standard but are available with sufficient purity and properties to be generally acceptable • • • Desirable properties of a Standard Solution: Prepared from primary standard Stable Reacts rapidily and completely with analyte Reacts selectively with analyte
![Volumetric Analysis Principles Examples of Standard Materials Primary Potassium Acid Volumetric Analysis - Principles Examples of Standard Materials • • • Primary Potassium Acid](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-17.jpg)
Volumetric Analysis - Principles Examples of Standard Materials • • • Primary Potassium Acid Phthalate KHC 8 H 4 O 4 (FW 204. 23) Benzoic Acid C 6 H 5 COOH (FW 122. 12) Na 2 CO 3 , KH(IO 3)2 Arsenious Oxide (As 2 O 3) Sodium Oxalate (Na 2 C 2 O 4) KI , K 2 Cr 2 O 7 , Fe(pure) • Secondary • Na. OH , KOH , Ba(OH)2 • HCl , HNO 3 , HCl. O 4 • Sulfamic Acid (HSO 3 NH 2) • KMn. O 4 , Na 2 S 2 O 3 • Ce(HSO 4)4 (FW 632. 6)
![Volumetric AnalysisPrinciples Standardization involves establishing the concentration of a standard solution Volumetric Analysis-Principles • Standardization – involves establishing the concentration of a “standard solution” •](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-18.jpg)
Volumetric Analysis-Principles • Standardization – involves establishing the concentration of a “standard solution” • Direct method: • dissolve caarefully weighed quantity of primary standard; dilute to known volume • Indirect methods: • Titrate weighed quantity of primary standard • Titrate weighed quantity of secondary standard • Titrate measured volume of other standard solution
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![Volumetric Analysis Principles Acid Base HA B BH Volumetric Analysis - Principles • • Acid – Base HA + B BH+ +](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-20.jpg)
Volumetric Analysis - Principles • • Acid – Base HA + B BH+ + APrecipitation Mn+ + X- MXn Oxidation-Reduction Red 1 + Ox 2 Ox 1 + Red 2 Complexation Mn+ + Q M(Q)n+ use standard Q solution
![Volumetric Analysis Principles Dilutions Vc x C c Vd x Volumetric Analysis - Principles • Dilutions • Vc x C c = Vd x](https://slidetodoc.com/presentation_image_h/e614d822180dd9005f6d1df366feaae4/image-21.jpg)
Volumetric Analysis - Principles • Dilutions • Vc x C c = Vd x C d • Stoichiometric Ratios (S. R. ) Mole Ratio: • What are stoichiometric ratios (mole ratios)? • 2 HCl + Ba(OH)2 2 HOH + Ba 2+ + 2 Cl • 2 Mn. O 4 - + 5 C 2 O 42 - + 16 H+ 2 Mn 2+ + 10 CO 2 + 8 HOH
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And now with gleams of half-extinguished thought
Five of five
5 senses and 5 elements
Macbeth