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Lecture 1 General Introduction

Clinical Analytical Chemistry CLS 231. Lecture 1 General Introduction. Lecturer: Amal Abu- Mostafa. Session Objectives:. Definition of Analytical Chemistry The Analytical Process Review of Fundamental Concepts Basic Tools and Operations of Analytical Chemistry

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Lecture 1 General Introduction

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  1. Clinical Analytical Chemistry CLS 231 Lecture 1General Introduction Lecturer: Amal Abu-Mostafa

  2. Session Objectives: • Definition of Analytical Chemistry • The Analytical Process • Review of Fundamental Concepts • Basic Tools and Operations of Analytical Chemistry • Concentrations of Solutions

  3. Definition of Analytical Chemistry • Analytical chemistry is often described as the area of chemistry responsible for characterizing the composition of matter, both qualitatively • (Is there any lead in this sample?) • and quantitatively (How much lead is in this sample?)

  4. The analytical process The analytical process involves a sequence of logical events including : 1. Defining the problem This means that the analyst should know what information is required, the type and amount of sample, the sensitivity and accuracy of the results, the analytical method which can be used to achieve these results, etc...

  5. 2. Obtaining a representative sample • It is very important to collect a representative sample for analysis. • 3. Preparing the sample for analysis • Most analytical methods require a solution of the sample rather than the solid. Therefore, samples should be dissolved quantitatively and may be diluted to the concentration range of the method.

  6. 4. Chemical separations The sample may contain solutes which interfere with the determination of the analyte. If this is the case, analytes should be separated from the sample matrix by an accepted procedure. 5. Performing the measurement This implies conducting the analytical procedure and collecting the required data. 6. Calculations The final event in the analytical process is to perform the calculations and present the results in an acceptable manner.

  7. Review of fundamental concepts • Qualitative analysis: An analysis in which we determine the identity of the constituent • Quantitative analysis: An analysis in which we determine how much of a constituent • Analytes: The constituents of interest in a sample. • Accuracydescribes how close a measured value is to the “true” value.

  8. Basic Tools and Operations of Analytical Chemistry • Basic Equipment • Measurements are made using appropriate equipment or instruments. The array of equipment and instrumentation used in analytical chemistry is impressive, ranging from the simple and inexpensive, to the complex and costly. • Equipments for Measuring Mass (Analytical Balance) • An object’s mass is measured using a balance.

  9. Title text to go here

  10. Preparing Solutions: • We have two ways to prepare solutions according to the nature of substances. • 1) Solid state: • Is prepared by weighing out an appropriate portion of a pure solid and diluting for a known volume. • m = M × M.wt × V ( L )

  11. Preparing Solutions: • 2) Liquid solution (Dilution of Solutions): • To prepare dilute solution from concentrated one, we need to add more solvent to the concentrated solution. • A new volume of the stock solution is transferred to a new container, and brought to a new volume. • Since moles are constant before and after dilution, we can use the following formula for calculations. • Mdil × Vdil =Mconc × Vconc

  12. Solution: • Mconc= 2M Vconc = ?? • Mdill = 0.4M Vdill = 100mL • Mdil × Vdil =Mconc × Vconc • 0.4 × 100 = 2 × Vconc • Vconc = 20 ml

  13. Home work • Diluting a solution does NOT change which of the following? • 1) concentration • 2) volume • 3) milliliters of solvent • 4) moles of solute

  14. Dilution Calculation What is the concentration of a solution prepared by diluting 25.0 mL of 6.00 M HCl to a total volume of 50.0 mL? • Given:Vconc= 25 mL • Mconc= 6.00 M • Vdill= 50.0 mL • Find: Mdill= ?? • Mdil × Vdil =Mconc × Vconc • Mdill × 50 = 6 × 25 • Mdill = 3 M Note:Vconc and Vdilldo not have to be in liters, but they must be in the same units.

  15. Concentrations of Solutions Behavior of solutions depend on compound itself and on how much is present, i.e. on the concentration. Two solutions can contain the same compounds but behave quite different because the proportions of those compounds are different.

  16. Concentrations of Solutions • Concentration of a solution: the more solute in a given volume of solvent, the more concentrated • Percentage concentration of solutions: • What are two ways to express the percent concentration of a solution? • The concentration of a solution in percent can be expressed in two ways: • -As the ratio of the volume of the solute to the volume of the solution. • -Or as the ratio of the mass of the solute to the mass of the solution.

  17. Concentration in Percent (Volume/Volume) • Isopropyl alcohol (2-propanol) is sold as a 91% solution. This solution consist of 91 mL of isopropyl alcohol mixed with enough water to make 100 mL of solution.

  18. Hhj

  19. Home work

  20. Percent Solutions • Concentration in percent (mass/mass) • For example, the concentration of sodium chloride in seawater is often given as 3% NaCl, which means 3g NaCl/100g seawater.

  21. Concentrations of Solutions • Dilute solution : the ratio of solute to solvent is small. • Concentrated solution: The ratio of solute to solvent is large.

  22. Molarity is one way to measure the concentration of a solution. A 1.00 molar (1.00 M) solution contains 1.00 mol solute in every 1 liter of solution. Units of molarity are: mol/L = M moles of solute mol Molarity (M) = Molarity (M) = volume of solution in liters Volume (L) Molarity

  23. Molarity Practice • 1) What is the molar NaCl concentration if you have 0.5 mol NaCl in 1.00 L of solution? • M = n = 0.5 = 0.5 M V(L) 1 • 2) What is the molar NaCl concentration if you have 0.5 mol NaCl in 0.50 L of solution? • M = 1 mol/L

  24. Molarity Practice 3) What is the molar NaCl concentration if you have 10.0 g of NaCl in 1.00 L of solution? Have grams not mols! • Grams  mol • Need molar mass Mwt of NaCl: 23.00 + 35.45= 58.45 g/mol n = m / Mwt = 10 /58.45 = 0.17 molNaCl Molar concentration: 0. mo17l/1.00 L = 0.17 M

  25. Practice 4)How many moles of HCl are present in 2.5 L of 0.10 M HCl? Given:v = 2.5 L of soln M = 0.10M HCl Find:n = ?? molHCl Use:n= Mx v (L) nHCl = 0.10 M HCl x 2.5 L = = 0.25 mol HCl

  26. Practice 5) What volume of a 0.2 M NaOH solution is needed to provide 0.50 mol of NaOH? 6) How many grams of CuSO4 are needed to prepare 250.0 mL of 1.00 M CuSO4?

  27. Solution: m NaCl= 0.9 g • V = 100 ml , M NaCl = ?? • M = n ,so, we should calculate number of moles of • V(L) NaCl • n= m = 0.9 = 0.0154 mol • Mwt 58.45 • M = 0.154 mol/L

  28. Homework

  29. Thank you

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