Analytical Chemistry - Section 2.pdf

University of Mines and Technology Analytical Chemistry (CH & RP 174) Section 2 Dr Benjamin Edem Meteku Department of Chemical & Petrochemical Engineering [email protected] June 2024 BASIC TOOLS AND OPERATION IN...

University of Mines and Technology Analytical Chemistry (CH & RP 174) Section 2 Dr Benjamin Edem Meteku Department of Chemical & Petrochemical Engineering [email protected] June 2024 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB ❖ Safe, Ethical Handling of Chemicals and Waste BEM 2 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB ❖ Safe, Ethical Handling of Chemicals and Waste BEM 3 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB GHS – Hazard Pictograms BEM 4 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB BEM 5 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB BEM 6 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB What Do We Use in Analytical Lab? BEM 7 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Handling Chemicals BEM 8 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Analytical Balance The Electronic balance is used to weigh materials. BEM 9 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Using a Balance BEM 10 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Glassware and Other Apparatus BEM 11 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Burette BEM 12 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Manipulating the Burette Stopcock BEM 13 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Conical flask Volumetric flask BEM 14 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Pipette BEM Micropipette 15 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Syringes BEM 16 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB BEM Desiccator 17 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Filter Paper BEM 18  BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Washing by Decantation and transferring the precipitate BEM 19 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Dispensing an aliquot BEM 20 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Reading Volume BEM 21 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB Reading Volume BEM 22 BASIC TOOLS AND OPERATION IN ANALYTICAL LAB The Lab NoteBook BEM 23 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Units of Measurement BEM 24 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Units of Measurement BEM 25 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Units of Measurement BEM 26 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY The Mole Concept BEM 27  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 1 Benzoic acid ( C6H5COOH) is an important antimicrobial preservative in the food and beverage industry especially used in carbonated drinks (pH of 2.5 - 4.0). How many moles and milimoles of benzoic acid (MW= 122.1g/mol) are contained in 2.0 g of the pure acid. Ans: 0.0164 mol 16.4 mmol BEM 28  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 2 Ans. …. g of Na+ BEM 29 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Solutions and Concentration BEM 30 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 3 Answer: 0.0143 M BEM 31 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Percent Concentrations BEM 32 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY BEM 33  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 4 Convert 78.0 ppm of Ca2+ ions to mol/L Answer: 78.0 ppm = 78 mg of Ca2+ / L of Solution = 0.078 g/L Hence concentration (mol/L) = (0.078 g/L ) / ( 40 g/mol) = 1.95 x 10-3 mol/L BEM 34  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 5 Calculate the molarity of a dye concentration given the molar mass is of the dye 327 g/mol and a dye concentration of 2 ppm. Answer: BEM 35 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 6 Answer: 5.77 x 10-4 M BEM 36 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 7 BEM 37  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 7 Ans: 0.044 mol of AgNO3 7.47 g of AgNO3 BEM 38 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Chemical Stoichiometry BEM 39 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Empirical and Molecular Formula BEM 40 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY BEM 41  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 1 Determine the empirical formula for a compound with the following composition (MW of C = 12.01, S = 32.06) Carbon = 15.8% and sulphur = 84.2% Solution: Total composition = 15.8% + 84.2% = 100% lets assume a basis of 100 g of sample Now, lets convert the compositions to mol BEM 42  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 1 Solution: For Carbon = (15.8g) / (12.01 g/mol) = 1.315 mol For Sulphur = (84.2g) / (32.06 g/mol) = 2.626 mol Mole ratio C : S = 1.315 mol : 2.626 mol C : S = 1 : 1.996 CS2 BEM 43  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 2 Determine the empirical formula for a compound with the following composition Carbon = 40.0%, Hydrogen = 6.7%, Oxygen = 53.3% (MW of C = 12.01, H = 1.008, O =15.999 g/mol) Solution: Total composition = 40.0 + 6.7 + 53.3 = 100% lets assume a basis of 100 g of sample Now, lets convert the compositions to mol BEM 44  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 2 Solution: For Carbon = (40.0 g) / (12.01 g/mol) = 3.33 mol For Hydrogen = (6.7 g) / (1.008 g/mol) = 6.647 mol For Oxygen = (53.3 g / (15.999 g/mol) = 3.33 mol Mole ratio C : H : O = 3.33 mol : 6.647 mol : 3.33 mol C:H:O= 1 :2:1 CH2O BEM 45  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 3 Polymers are large molecules composed of simple units repeated many times. Thus, they often have relatively simple empirical formulas. Calculate the empirical formulas of the following polymers: (a) Lucite (Plexiglas); 59.9% C, 8.06% H, 32.0% O (b) Saran; 24.8% C, 2.0% H, 73.1% Cl (c) polyethylene; 86% C, 14% H (d) polystyrene; 92.3% C, 7.7% H (e) Orlon; 67.9% C, 5.70% H, 26.4% N BEM 46  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 3 Solution: BEM 47  BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Example 4 Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following percent composition: 28.03% Mg, 21.60% Si, 1.16% H, and 49.21% O. The molar mass for chrysotile is 520.8 g/mol. Answer Mg3Si2H3O8 (empirical formula), Mg6Si4H6O16 (molecular formula) BEM 48 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Dilutions BEM 49 BASIC CALCULATIONS IN ANALYTICAL CHEMISTRY Dilutions BEM 50  ACKNOWLEDGEMENT Materials for the lecture presentations were adapted from the works of the following; 1. Dr Cornelius B. Bavoh 2. Dr Gideon Abaidoo Ocran 3. Dr Hayyiratul Fatimah Zaid BEM 51