Course Content
Matter
OBJECTIVES By the end of this topic, the trainee should be able to 1.Define matter 2.Explain state of matter 3.Distinguish between physical and chemical changes 4.Explain the gas laws
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Atoms , Elements and Compounds
OBJECTIVES By the end of this topic , the trainee should be able to; 1.Define Elements, Compounds and Mixtures 2.Describe the structure of an atom 3.Describe how to determine the Atomic number ,Mass number and Isotopes
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The Periodic Table
OBECTIVES By the end of this topic, the trainee should be able to : 1.State the historical contribution on development of the periodic table 2.Explain the periodic trends of elements and their compounds 3.State the diagonal relationships of the periodic table
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The S-Block Element
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Explain the chemistry of group I and II elements 2.State the application of group I and two elements and their compounds
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Chemical Bonds
OBJECTIVES By the end of these topic, the trainee should be able to 1.Identify different types of bonds 2.Describe their properties
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Chemical Equilibrium
OBJECTIVES By the end of this topic , the trainee should be able to : 1.Define chemical equilibria 2.Explain types of equilibria 3.Determine equilibrium constant 4.Describe factors affecting chemical equilibrium
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Introduction To Organic Chemistry
By the end of this topic , the trainee should be able to : 1.Explain the aspects of organic chemistry 2.Describe hydrocarbons 3.Classify organic molecules explain chemical reactions of simple organic molecules 4.Explain the properties , synthesis and uses of simple organic molecules
0/10
Acids, Bases and Salts
OBJECTIVES By the end of this session , the trainee should be able to : 1.State properties of acids and bases 2.Differentiate between strong and weak acids 3.Explain types and properties of salts
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PH Analysis
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define the term PH 2.Explain the basic theory of PH 3.State the relationship between PH and color change in indicators 4.Explain the term buffer solution 5.Describe the preparation of buffer solutions 6.State the application of buffer solutions
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Sampling and Sample Preparation
OBJECTIVE By the end of this topic, the trainee should be able to : 1.Define the terms used in sample preparation 2.State the importance of sampling 3.Describe the techniques of sampling 4.Describe the procedure for sample pre-treatment 5.State sample storage methods
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Separation Techniques
OBJECTIVES By the end of this topic , the trainee should be able to : 1.Define separation, extraction and purification 2.Describe the separation , extraction and purification techniques 3.Explain the methods of determining purity of substances
0/2
Heating and Cooling Techniques
OBJECTIVES To identify various techniques used for heating and cooling substances in the laboratory
Heating and Cooling Techniques
OBJECTIVES To identify various techniques used for heating and cooling substances in the laboratory
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Distillation Techniques
By end of this topic, Trainee should be able to : 1. Define distilation 2. State and explain various distillation techniques 3. Outline Various distillation techniques 4. Outline the applications of Distillation techniques
0/3
Crystallization Techniques
OBJECTIVES By the end of the topic, the learner should be able to: 1.To define crystallization 2.To describe crystallization process 3.To carry out crystallization procedure
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Solvent Extraction Techniques
OBJECTIVES By the end of the topic, the learner should be able to 1.Define solvent extraction 2.Explain terms used in solvent extraction 3.Describe methods of solvent extraction 4.Describe selection of appropriate solvents for solvent extraction 5.Determine distribution ration 6.Outline factors actors influencing the extraction efficiency 7.Describe Soxhlet extraction
0/1
Chromatography Techniques
OBJECTIVES By the end of this topic, the learner should be able to: 1.Define chromatography techniques 2.Explain terms used in chromatography techniques 3.Describe principles of chromatography techniques 4.Explain types of chromatography techniques 5.Carry out chromatography experiments 6.Determine RF factor 7.Outline electrophoresis
0/6
Titrimetric Analysis
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define terms used in titrimetric analysis 2.Describe types of titrimetric analysis 3.Balance chemical reactions 4.Work out calculations involved in titrimetric analysis
0/6
Redox Titration
Redox Titration is a laboratory method of determining the concentration of a given analyte by causing a redox reaction between the titrant and the analyte. Redox titration is based on an oxidation-reduction reaction between the titrant and the analyte. It is one of the most common laboratory methods used to identify the concentration of unknown analytes. Redox reactions involve both oxidation and reduction. The key features of reduction and oxidation are discussed below.
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Complexiometric Titration
omplexometric Titration or chelatometry is a type of volumetric analysis wherein the colored complex is used to determine the endpoint of the titration. The method is particularly useful for determination of the exact number of a mixture of different metal ions, especially calcium and magnesium ions present in water in solution .
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Gravimetric Analysis
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define gravimetric analysis 2.Describe the principles of gravimetric analysis 3.Describe the steps involved in gravimetric analysis 4.Explain factors affecting gravimetric analysis 5.Describe the equipments and apparatus used in gravimetric analysis 6.Carry out gravimetric analysis
0/8
Calorimetric Analysis
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define terms and units used in thermochemistry 2.Determine enthalpy changes in chemical reactions 3.Determine heat capacity and specific heat capacity 4.Compare calorific values of different materials 5.Determine different heat reactions 6.Apply law of conservation of energy and Hess law in thermochemical calculations
0/4
Chemistry Techniques for Science Laboratory Technicians
About Lesson

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Example of  gravimetric analysis

An example of a gravimetric analysis is the determination of chloride in a compound. In order to do a gravimetric analysis, a cation must be found that forms an insoluble compound with chloride. This compound must also be pure and easily filtered. The solubility rules indicate that Ag+, Pb2+, and Hg22+ form insoluble chlorides.

Therefore silver chloride could be used to determine % Cl, because it is insoluble (that is, about 99.9% of the silver is converted to AgCl) and it can be formed pure and is easily filtered.

  1. Put enough unknown into a weighing bottle with the lid on sideways and dry in the oven. Cool in a desiccator.
  2. Indirectly weighsome mass, determined to 0.1 mg, of unknown into beaker.
  3. Dissolve the unknown.
  4. Add a precipiating agent to the solution.
  5. Optional – heat the solution on a hot plate to increase the particle size for easier filtering .This is usually referred to as digestion.
  6. Test for complete precipitation by adding a drop of the precipitating agent and looking for any sign of precipitate.
  7. Filter the solution using vacuum filtration. Use a rubber policemanto make sure all the precipitate has been transferred from the beaker to the filter. It is important that the precipitate is quantitatively transferred to the filter. If any remains in the beaker, the mass obtained will be inaccurate.
  8. Dry and weigh the precipitate.
  9. Use stoichiometry to determine the mass of the ion being analyzed.
  10. Find percent by mass of analyte by dividing the mass of the anayte by the mass of the unknown.

The following calculations would be done for this gravimetric determination of chloride:

Mass of sample of unknown chloride after drying =0.0984 g
Mass of AgCl precipitate =  0.2290 g

One mole of AgCl contains one mole of Cl.

Therefore:

(0.2290 g AgCl)

(143.323g/mol) = 1.598×10-3 molAgCl

(1.598 x 10-3 mol AgCl) x (35.453 g/mol Cl) = 0.0566 g Cl

(0.0566 g Cl)  x 100%

(0.0984 g sample)

= 57.57% Cl in unknown chloride sample

Notice that even though the mass of sample (0.0984) only contains three significant figures, the number is known to one part in a thousand (0.0001/0.0984 = 1/1000). The number 0.0984 therefore actually is “good” to four significant figures and the answer can be expressed to four significant figures.

If Pb2+ had been used to precipitate the chloride, the calculuation would need to be modified to account for the fact that each mole off PbCl2 contains two moles of chloride. Lead would not be a good precipitating reagent, however, because PbCl2 is moderately soluble and therefore a small amount of chloride would remain in solution, rather than in the precipitate.

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