Lecture 38-39 Chemical Analysis (1).pptx

about chemical analysis

1. Types of chemical analysis methods; qualitative and quantitative chemical analysis of certain chemical reagents, Dr. Muhammad Tahir Saddique Assistant Professor (Chemistry) Department of Applied Sciences

2. Contents Chemical Analysis

3. Chemical Analysis Chemical analysis is the process of identifying, separating and quantifying the components of a sample to evaluate its nature and composition. The branch of chemistry that deals with chemical analysis is called analytical chemistry. Steps of Chemical Analysis Collecting a sample of interest. Picking an appropriate analytical method to analyse the sample. Prepping the sample.

4. Chemical Analysis Analysing the sample using appropriate chosen method, test, or technique. Interpreting the results of the analysis. This might involve calculations or further tests. Types of chemical analysis: qualitative and quantitative Chemical analysis is classified into two major types Qualitative chemical analysis. Quantitative chemical analysis.

5. Chemical Analysis Qualitative chemical analysis is a type of analysis used to identify the substances within a sample and determine whether a particular substance is present or not. Quantitative chemical analysis is a type of analysis used to determine the quantity or the amount of a substance in a sample.

6. Chemical Analysis: Tests, Methods, and Techniques esting for pure substances using melting and boiling points. Testing for gases using simple test tube reactions. Testing for ions using reactions that you can carry out in class, such as flame tests, the sodium hydroxide test, and tests for anions. Instrumental analysis, such as chromatography and flame emission spectroscopy.

7. Instrumental Analysis The tests for gases and the sodium hydroxide test are all simple reactions. They are quick and convenient to use, but they are qualitative, not quantitative. If quantitative measure of the sample, then to use certain analytical instruments. They not only identify components of a sample, but also measure their relative amounts. Using analytical instruments in chemical analysis is called instrumental analysis. Instrumental methods have certain advantages over test tube reactions. As mentioned above, some are both qualitative and quantitative, whilst most are extremely accurate, sensitive and rapid. In addition, they can work with small samples and are highly versatile.

8. Instrumental Techniques NMR, IR, UV, x-ray fluorescence, and flame emission spectroscopy are all types of spectroscopic techniques. They use the interactions between electromagnetic (light) waves and particles to help us identify the structure of atoms and molecules. Chromatography works by separating a sample into its components. As well as paper chromatography, thin-layer chromatography, gas chromatography, gas-liquid chromatography, and many other variations, For example, if want to separate a mixture of amino acids, you typically use paper or thin layer chromatography.

9. Chemical Methods of Qualitative Analysis Qualitative analysis typically measures changes in color, melting point, odor, reactivity, radioactivity, boiling point, bubble production, and precipitation. Methods include distillation, extraction, precipitation, chromatography, and spectroscopy.

10. Quantitative Chemical Analysis Quantitative chemical analysis, branch of chemistry that deals with the determination of the amount or percentage of one or more constituents of a sample. A variety of methods is employed for quantitative analyses, which for convenience may be broadly classified as chemical or physical, depending upon which properties are utilized. Chemical methods depend upon such reactions as precipitation,

11. Quantitative Chemical Analysis neutralization, oxidation, or, in general, the formation of a new compound. The major types of strictly chemical methods are known as gravimetric analysis and volumetric, or titrimetric, analysis (see volumetric analysis). Physical methods involve the measurement of some physical property such as density, refractive index, absorption or polarization of light, electromotive force, magnetic susceptibility, and so on. An analysis often require a combination of methods: qualitative for separating desired constituents from

12. Quantitative Chemical Analysis a sample and quantitative for measuring the amounts present. The basic tool in all quantitative analyses is the analytical balance, used for the accurate weighing of samples and precipitates. For usual analytical work the balance should be able to determine differences in mass of 0.1 milligram. In microanalyses the balance must be about 1,000 times more sensitive, and, for special work, balances of even higher sensitivity.

13. Types of Quantitative Chemical Analysis Chemical methods depend upon such reactions as precipitation, neutralization, oxidation, or, in general, the formation of a new compound. The major types of strictly chemical methods are known as gravimetric analysis and volumetric, or titrimetric, analysis.

14. Quantitative Analysis of a Chemical Substance Quantitative analysis is any method used for determining the amount of a chemical in a sample. The amount is always expressed as a number with appropriate units. An acid-base titration is an example of quantitative analysis.

15. Difference between Qualitative and Qualitative Analysis Generally speaking, quantitative analysis involves looking at the hard data, the actual numbers. Qualitative analysis is less tangible. It concerns subjective characteristics and opinions things that cannot be expressed as a number. Qualitative analysis in chemistry uses techniques such as distillation, extraction, and change in colour, chromatography, etc. Quantitative analysis in chemistry uses techniques such as titrations, gravimetric analysis, combustion analysis, AES, etc.

16. Phenolphthalein phenolphthalein, (C 20 H 14 O 4 ), an organic compound of the phthalein family that is widely employed as an acid-base indicator. As an indicator of a solution’s pH, phenolphthalein is colourless below pH 8.5 and attains a pink to deep red hue above pH 9.0. Phenolphthalein, which is closely related to the triphenylmethane dyes, prepared it by fusing phenol and phthalic anhydride in the presence of sulfuric acid or zinc chloride.

17. Qualitative Chemical Analysis Qualitative chemical analysis, branch of chemistry that deals with the identification of elements or grouping of elements present in a sample. The techniques employed in qualitative analysis vary in complexity, depending on the nature of the sample. In some cases it is necessary only to verify the presence of certain elements or groups for which specific tests applicable directly to the sample (e.g., flame tests, spot tests) may be available. More often the sample is a complex mixture, and a systematic analysis must be made in order that all the constituents may be identified. It is customary to classify the methods into two classes: qualitative inorganic analysis and qualitative organic analysis.