ANACHEM_Intro to Quantitative Analysis

• Quantitative chemical analysis- deals with the determination of the amount or percentage of one or more constituents of a sample.  It refers to how much of a given component is present in a sample.
• Titration- a solution of acid was  titrated with a solution  of  base and computed the amount of acid in the sample from the measured volume of base used
• Chemical Methods result in the formation of a new compound. It involves reactions such as precipitation, neutralization and oxidation
• Physical methods involve the measurement of physical properties such as density, refractive index, absorption or polarization of light, electromotive force, magnetic susceptibility, etc.
• In gravimetric analysis the constituent being analyzed is converted into a substance (of known composition) that can be separated from the sample and weighed.
• Volumetric analysis also known as titrimetric analysis is a method in which the amount of a substance is determined by measuring the volume that it occupies or the volume of a second substance that combines with the first in known proportions.
• steps involved in gravimetric analysis

  1. Preparation of a solution containing a known weight of the sample
  2. Separation of the desired constituent
  3. Weighing the isolated constituent
  4. Computation of the amount of the particular constituent in the sample from the observed weight of the isolated substance.
• types of volumetric analysis

  • Neutralization reactions is a reaction between an acid and a base forming salt and water
  • Precipitation reactions make use of silver nitrate  as a reagent that react with the ions present in the sample to form a high insoluble precipitate, thus precipitation reaction is also called  Argentometry.
  • Complex forming reaction  occurs between metal ions and EDTA (ethylene diamine tetra acetic acid).
  • Redox reaction is carried out between an oxidizing agent  and a reducing agent
• An accurate balance- used to weigh materials for analysis
• graduated instruments - Used to measure volumes of the solutions
• steps involved in doing a quantitative chemical analysis

  1. choosing a method
  2. acquiring the sample
  3. preparing the lab sample
  4. defining replicate samples
  5. preparing solutions of a sample
  6. eliminating interferences
  7. calibration, measurement and calculating results
  8. evaluation of results and estimation of reliability
• applications of quantitative analysis in medicine

  • Blood samples are analyzed for the concentrations of oxygen and carbon dioxide in order to diagnose and treat illnesses.
  • Ionized calcium in the blood serum is measured to diagnose parathyroid disease in humans. 
  • Analysis on biological samples can determine the relative abundance ratio of specific proteins which serve as indications of certain diseases like cancer.
• applications of quantitative analysis in industry

  • Nitrogen in foods is determined quantitatively to establish their protein content and nutritional value.
  • In the manufacture of steel, analysis of its elementary constituents such as carbon, nickel, and chromium is very important in achieving its good quality of strength, hardness, corrosion resistance and ductility.
• applications of quantitative analysis in agriculture

  • Farmers schedule their agricultural activities such as fertilization and irrigation to meet the changing plant needs during the growing season which were gauged from the quantitative analysis of the plants and soil in which they grow.
• applications of quantitative analysis in the environment

  • Effectiveness of smog-control devices is determined from the quantitative measurement of hydrocarbons, nitrogen oxide and carbon monoxide present in automobile exhaust.
  • Household gas supplies are continuously monitored for its mercaptan content to ensure that the gas has a sufficiently obnoxious odor that will warn dangerous leaks. 
• Applications of quantitative analysis in research

  1. Physiologists explore the role of potassium, calcium, and sodium ions in nerve-signal conduction and muscle contraction/relaxation through quantitative measurements of these ions in body fluids

  2. Chemists explain the rate of consumption of reactants or formation of products in a chemical reaction through calculations from quantitative measurements of reactants and products made at equal intervals

  3. Archaeologists identify the source of volcanic glasses or obsidian from the concentration of minor elements in samples taken from various locations
• Quantitative analysis of crystalline germanium and silicon

  Important in the study of semiconductor devices