Analytical Chemistry PPT_PEPITO AND CONSULTA PDF

ANALYTICAL CHEMISTRY Prepared by: JAMES B. PEPITO | GRACE CONSULTA BSED-SCIENCE 4B INTRODUCTION What is analytical chemistry? Analytical Chemistry is the study of various techniques and laboratory methods to determine the composition of matter. In industry, analytical...

ANALYTICAL CHEMISTRY Prepared by: JAMES B. PEPITO | GRACE CONSULTA BSED-SCIENCE 4B INTRODUCTION What is analytical chemistry? Analytical Chemistry is the study of various techniques and laboratory methods to determine the composition of matter. In industry, analytical chemistry provides the means of testing raw materials for assuring the quality of finished products whose chemical composition is critical (e.g., Drugs) In medicine, analytical chemistry is the basis for clinical laboratory tests which help the physicians diagnose disease. APPLICATIONS OF ANALYTICAL CHEMISTRY COMMON LABORATORY APPARATUS 01  EVAPORATING LIQUIDS Beaker A cylindrical container with a wide mouth and flat bottom. Beakers often have a lip for easy pouring and are available in various sizes. 01  EVAPORATING LIQUIDS 01 01 Bunsen Burner 02 A small, adjustable gas burner that produces a single open flame. It is commonly used in labs for heating, sterilization, and combustion purposes. 02 Alcohol Lamp An alcohol lamp is used for heating, sterilization, and combustion in a laboratory. The alcohol lamp uses ethyl alcohol or spirit as a fuel. 01  EVAPORATING LIQUIDS Evaporating dish It is used as reaction vessels, or for the separation of the solute from a solution through crystallization. 01 MEASURING MASS Analytical Balance highly sensitive lab instruments designed to accurately measure mass. An analytical balance has a maximum capacity that ranges from 1g to several kilograms and a precision at maximum capacity of a least 1 part in 105.  TYPES OF ANALYTICAL BALANCE 01 01 Microbalance A Microbalance has a maximum load of g and a precision of 0.1 mg. 02 Semi- Microbalance A semi microanalytical balance 02 has a maximum load of g and a precision of 0.01 mg.  TYPES OF ANALYTICAL BALANCE 03 03 Micro Analytical balance A microanalytical balance has a maximum load of 1-3 g and a precision of mg, or 1 µg.  MEASURING MASS 01 Weighging Boat 01 open containers that are used to weight granulated, liquid, or solid samples. 02 Auxillary Balance used to weigh solid material when 02 a precision of 0.1 g is adequate MEASURING VOLUME Graduated Pipette used in laboratory to measure the volume or transfer a particular quantity of liquid from one container to another. MEASURING VOLUME Volumetric Pipette use extremely accurate measurement (to four significant figures) of the volume of a solution. MEASURING VOLUME Volumetric Flask used when it is necessary to know both precisely and accurately the volume of the solution that is being prepared MEASURING VOLUME Graduated Cylinder common piece of laboratory equipment used to measure the volume of a liquid  SAMPLES ARE PUT INTO Erlenmeyer Flask – used Test tube – used Reagent bottle- to contain liquids and for as a container for used to store mixing, heating, cooling, small amounts of a chemicals in liquid incubation, filtration, substance in or powder form. storage, and other liquid- laboratory handling processes.  FILTRATION AND IGNITION APPARATUS Filter paper- used to separate fine solid particles from liquids or gases. Crucible- a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures CLASSIFICATION OF SOLUTIONS 01  SOLUTIONS A homogeneous mixture in which the components are uniformly distributed. A substance, usually a liquid, that dissolves a solute to form a solution is called solvent. On the other hand, a substance that is being dissolved in a solvent to form a solution is called a solute. 02 SOLUTIONS UNSATURATED SOLUTIONS A solution that has not reached the limit of solute that will dissolve in the solution. It is characterized by a solute concentration that is lower than the maximum amount that can be dissolved in a given solvent at a specific temperature and pressure. SOLUTIONS SATURATED SOLUTIONS Saturated solutions contain the maximum amount of solute that can dissolve in a solvent at a specific temperature and pressure, reaching a point where no additional solute can be dissolved. SOLUTIONS SUPERSATURATED SOLUTIONS Supersaturated solutions are characterized by a solute concentration that exceeds the maximum amount that can dissolve in a solvent at a specific temperature and pressure.  SOLUTIONS CONCENTRATED SOLUTIONS — A relatively large amount of solute is dissolved in a solution. DILUTED SOLUTION — A relatively small amount of solute is dissolved in a solution. DIFFERENT WAYS OF EXPRESSING CONCENTRATIONS 01  Mass of solute PERCENT CONCENTRATION A. Percent w/w = Mass of solution It refers to the amount of Volume of solute B. Percent v/v = solute per 100 parts of the Volume of solution solution. Mass of solute C. Percent w/v = A. Weight by Weight Percentage Volume of solution B. Volume by Volume Percentage C. Weight by Volume Percentage D. Percent v/w = Volume of solute Mass of solution D. Volume by Weight Percentage PARTS PER MILLION It is expressed as: It is used to express the concentration of Mass of solute dilute solutions. ppm = x 10^6 Mass of solution PARTS PER BILLION It is used to express It is expressed as: the concentration of dilute solutions. Mass of solute ppb = x 10^9 Mass of solution Molarity is expressed as M. MOLARITY Number of moles of solute M= It refers to the number of 1000 mL of Solution moles of solute 1 g in 1000 mL = 1 mol (substance) dissolved in Dilution problems: one liter (1000 mL) of M 1 V 1 = M 2V 2 solution. Molar Mass: n= m Where: MW n= number of moles m= mass MW= Molecular Weight SAMPLE PROBLEMS EXAMPLE #1 EXAMPLE #2 Determine the molarity of 3.72 How many milliliters of concentrated H2SO4 (16.0 M) moles of NaBr in 575 mL of solution. is required to prepare 250 mL of 6.00 M H2SO4 solution? Solution: desired: M V = 250 mL Number of moles of solute 1 = 6.00 M ; 1 M= 1000 mL of Solution on hand: M = 16.0 M ; V = ? 2 2 3.72 mol M [NaBr]= M1 V 1 (6.00 M)(250 mL) 0.575 L V2 = = = 93.8 mL of H2S04 M2 (16.00 M) M [NaBr]= 6.47 mol/L or 6.47 M NORMALITY ( N ) N = M x #H+ # e.w of solute It is the number of gram N= v equivalent of solute dissolved Where: in one liter (1000 mL) of N = Normality solution. It is indicated by N. # e.w = number of equivalent weight V = volume (L) EXAMPLE # 1: SOLUTION 2: N = M x #H+ What is the normality of a mass of solute solution containing 50 g of (1) number of moles = molar mass of HCl 50 g HCl in 1.5 L of solution? number of moles = 36.36 g/mol number of moles (2) Molarity = volume of sol 1.37 mol Molarity = 1.5 L (3) N = (M)(#H+) N = (0.914)(1) N = 0.914 MOLALITY moles of solute N= kg of solvent A molal solution contains 1 mole of solute per one kilogram of solution mol (1 liter of solvent). N= kg Molality is expressed as m.  EXAMPLE 1: mole of solute molality = kg of solvent 1 mol of CaCl2 (1) number of moles =18 g CaCl2 x 111 g CaCl2 What is the molality of a number of moles = 0.16 mol solution when 18g of (2) mass of solvent = 450 mL calcium chloride is 1000 g dissolved in 450 mL of mass of solvent =0.45 kg water.. mass of solute (3) molality = kg of solvent 0.16 mol molality = 0.45 kg molality = 0.36 mol/kg HOW MANY DIGITS DO WE RETAIN WHEN USING THE RECORDED MASS OR VOLUME IN CALCULATIONS WHEN YOU ARE DOING EXPERIMENTS? SIGNIFICANT FIGURES 01  Significant Figures are the digits of a number that are meaningful in terms of accuracy or precision ▪︎The importance of significant figures in reporting measurement is the number of significant figures corresponds to all digits that are certain in a measurement plus one uncertain digit. Let's learn & have some examples! VALUE SIGNIFICANT FIGURES 1. 3080 FOUR 2. 4009 _________ 3. 37 TWO 4. 6.870 _________ 5. 0. 43 _________ Let's learn & have some examples! VALUE SIGNIFICANT FIGURES 1. 3080 FOUR 2. 4009 FOUR 3. 37 TWO 4. 6.870 FOUR 5. 0. 43 TWO RULES FOR SIGNIFICANT FIGURES 1. All non-zero digits are significant. Example: 198745 – 6 significant figures 2. All zeros that occur between any two non-zero digits are significant. Example: 108.0097 –7 significant figures 3. All zeros that are on the right of a decimal point and also to the left of a non-zero digit is never significant. Example: 0.00798-3 significant figure 4.All zeros that are on the right of a decimal point are significant, only if, a non-zero digit does not follow them Example: 80.00 – 4 significant figures 5. All the zeros that are on the right of the last non-zero digit, after the decimal point, are significant Example: 0.0098700 -5 significant figures 6.All the zeros that are on the right of the last non-zero digit are significant if they come from a measurement Example: 2080-4 significant figure significant figure calculations ADDITION AND example SUBTRACTION When adding or a. 4.2 + 8.236 + 7.91 = 20.346 subtracting digits, the LEAST : 4.2 = 1 decimal place results shall have the same number of decimal FINAL ANSWER: 20.3 places as the given measurement with the b. 15.6 – 7.27 = 8.33 least number of decimal places. Otherwise, the LEAST : 15.6 = 1 decimal place result will have to be FINAL ANSWER: 8.3 rounded off. MULTIPLICATION example AND DIVISION When multiplying and dividing numbers, the (253)(3.45) = 12.1229167 answer should bear the 72 same number of significant figures, as the given measurement with LEAST SIGNIFICANT FIGURE: 72 the least number of FINAL ANSWER: 12 significant figures. Otherwise, the result must be rounded off ACCURACY AND PRECISION  ACCURACY is the closeness of a given measurement to the true value.  EXAMPLE During a proficiency test using a reference sample containing 24.54 ppm of lead, a chemist found the concentration of the Pb in the sample is 24.46 ppm.  MEASURE OF ACCURACY ABSOLUTE ERROR E= xi – xt provide an idea where; whether the measure E= absolute error, value is higher or xi = measured value, lower compared to xt = true value the true value.  EXAMPLE Given: xi= 24.46 ppm Lead determination analysis (previous xt= 24.54 ppm example) During a proficiency test Required: E=? using a reference sample containing 24.54 ppm of lead, a chemist found the Solution: concentration of the Pb in the sample is E= xi – xt 24.46 ppm. E= 24.46ppm- 24.54 ppm E= -0.08 ppm  MEASURE OF ACCURACY RELATIVE ERROR is simply the absolute error divided but the where; true value and can be Er= relative error, expressed in percent, xi = measured value, ppt, or ppm xt = true value  Given: EXAMPLE xi= 24.46 ppm xt= 24.54 ppm Lead determination analysis Required: E=? (previous example) During a Solution: proficiency test using a reference sample containing 24.54 ppm of lead, a chemist found the concentration of the Pb in the sample is 24.46 ppm. PRECISION is the closeness of replicate measurement with each other. It is also referred to as reproducibility  EXAMPLE The chemist recorded the following concentration of Pb: 24.89 ppm,24.22 ppm, 24.56 ppm, 24.15 ppm, and 24.49 ppm SUMMARY IMPORTANT In analytical chemistry, we need to be both accurate and precise. This can be accomplished by careful performance of the procedure to avoid error in conducting chemical analysis. ANALYTICAL TECHNIQUES AND METHODS 01 Classical Techniques Titrimetry- Involves quantitative chemical analysis through titration, including acid-base, complexometric, and redox titrations. Gravimetry- Based on the measurement of mass, often used for determining the quantity of an analyte based on its conversion to a stable compound. Electrochemical Methods Potentiometry- Measures the voltage of electrochemical cells to determine analyte concentration. Voltammetry and Amperometry- Techniques that measure current as a function of applied voltage to analyze substances. Spectrometric Techniques Spectrometric Techniques- Includes techniques such as flame atomic emission spectrometry and atomic absorption spectrometry for elemental analysis. Molecular Spectrometry- echniques like UV- Vis, infrared, and Raman spectrometry to analyze molecular structures and concentrations. Mass Spectrometry- Used for determining the mass-to-charge ratio of ions, providing information on molecular weight and structure. Chromatographic Techniques Gas Chromatography -Separates volatile compounds based on their partitioning between a stationary phase and a mobile gas phase. High-Performance Liquid Chromatography (HPLC)- Similar to GC but used for non-volatile and thermally unstable compounds. Thin-Layer Chromatography (TLC)-A simple and quick method for separating small amounts of substances. Thin-Layer Chromatography (TLC)-A simple and quick method for separating small amounts of substances. SAMPLE HANDLING TECHNIQUES 01  Sample Representative - Ensuring that the sample collected is representative of the whole is crucial. This involves careful planning of how samples are taken to avoid bias.  Sample Storage - Proper storage conditions (temperature, light exposure, humidity) must be maintained to ensure sample integrity until analysis.  Sample Preservation - Samples must be preserved to prevent degradation or changes in composition. This may involve refrigeration, freezing, or the use of preservatives.  Sample Preparation - Samples may require specific preparation techniques such as dilution, filtration, or extraction to make them suitable for analysis.  Sample Size and Quantity - Determining the appropriate sample size is vital for accurate analysis. The amount of material available and the number of samples to be analyzed must be considered. TYPES OF ERRORS 01 WHAT IS ERROR? ERROR refers to the difference between a measured value and the “true” or ERROR often denotes the estimated uncertainty in a “known” value. measurement or experiment  RANDOM ERROR (INTERMEDIATE) caused by uncontrollable or unknown fluctuations in variables that may affect experimental results. Error affects the precision of data sets. inevitable in measurements and Example: temperature are difficult to identify fluctuations which affect the Causes scattering of data around mass of solids being weighed or the mean value volumes of liquids being measured.  SOURCES OF RANDOM ERROR natural variations in real world or experimental contexts. imprecise or unreliable measurement instruments. individual differences between participants or units SYSTEMATIC ERROR (DETERMINATE) are those errors that are known and controllable errors. Error affects the Example: The student consistently accuracy of data reads the volume by looking at the liquid level near the edge of the sets. glass cylinder, rather than at the center of the meniscus as instructed.  TYPES OF SYSTEMATIC ERROR OFFSET ERRORS SCALE FACTOR ERROR occurs when a scale isn’t is when measurements consistently calibrated to a correct differ from the true value proportionally zero point. It’s also called (e.g. by 10%). It’s also referred to as a an additive error or a correlational systematic error or a zero-setting error. multiplier error.  INSTRUMENTAL ERROR CLASSIFICATION OF SYSTEMATIC METHOD ERROR ERROR PERSONAL ERROR INSTRUMENTAL ERROR Instrumental Errors are errors caused by poor instrument condition and calibration. METHOD ERROR Method Errors are caused by poor outcomes caused by substandard conditions of chemicals and reactions Example: In volumetric analysis, the use of improper indicator leads to wrong results. PERSONAL ERROR Personal Errors are caused by personal limitations of the analyst such as failing to follow procedures properly, among others. Example: Parallax Error The error/displacement caused in in the apparent position of the object due to the viewing angle that is other than the angle that is perpendicular to the object. DETECTION OF SYSTEMATIC ERRORS 01 ANALYSIS OF REFERENCE STANDARDS reference standards are chemicals of known concentration and purity Example: pH buffer solution ANALYSIS OF BLANK SAMPLES blank samples contain all reagents used in the analysis other than the sample. THIRD PARTY ANALYSIS allows other chemists to analyze the sample. VARIATION OF SAMPLE SIZE to check for constant or proportional errors Constant error- an average of the errors over the range of all data. Errors that do not change in magnitude as sample size increases Proportional Error an error that is dependent on the amount of change in a specific variable. Errors that increase in magnitude as sample size increase Example: Titration GROSS ERRORS causes large errors leading to outlier data. These are errors that are so serious (i.e. large in magnitude) that they cannot be attributed to either systematic or random errors associated with the sample instrument, or procedure. Example: When the contents of a mixture is spilled when it is being boiled. The loss brought about by spilling causes an error in the amount of the analyte present in the sample being boiled. THANK YOU!