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
0/4
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
0/6
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
0/1
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
0/1
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.
0/5
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 .
0/5
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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PH and Its Importance

When dealing with range of concentrations (such as these of H+(aq) ions) that spans many powers of ten, it is convenient to represent them on a more compressed logarithmic scale. By convention, we use the pH scale for denoting the concentration of hydrogen ions. pH notation was devised by the Danish biochemist Soren Sorensen in 1909. The term pH means “power of hydrogen”.

The pH is the logarithm of the reciprocal of the hydrogen ion concentration.It is written as:

PH= log 1

                                                         H+

Alternately, the pH is the negative logarithm of the hydrogen ion concentration

i.e pH = –log [H+].

Because of the negative sign in the expression, if [H+] increases, pH would decrease and if it decreases, pH would increase.

[H+] = 1.0 × 10–7 mol L–1

log[H+] = log(10–7) = –7

and pH  = –log[H+] = –(–7)

pH  = 7

Since in pure water at 25°C (298 K)

[OH] = 1.0 X 10-7molL-1

 

Also,

pOH = 7

Since,

Kw = 1.0x 10-14

 

pKw = 14

The relationship between pKw, pH and pOH is

pKw = pH + pOH

at 25°C (298 K)

                       14 = pH + pOH

Calculate the pH of 0.001 molar solution of HCl.

Solution: HCl is a strong acid and is completely dissociated in its solutions according to the process:

HCl(aq)→ H+(aq) + Cl(aq)

From this process it is clear that one mole of HCl would give one mole of H+ ions. Therefore, the concentration of H+ ions would be equal to that of HCl i.e. 0.001 molar or 1.0 × 10–3 mol L–1.

Thus, [H+] = 1 × 10–3 mol L–1

                               pH = –log[H+] = –(log 10–3)

                                = –(–3 × log10) = –(3 × 1) = 3

Thus,                           pH = 3

What would be the pH of an aqueous solution of sulphuric acid which is 5 × 10–5 mol L–1 in concentration.

Solution:Sulphuric acid dissociates in water as:

H2SO4(aq)→ 2H+(aq) + SO42–(aq)

Each mole of sulphuric acid gives two mole of H+ ions in the solution. One litre of 5 × 10–5 mol L–1 solution contains 5 × 10–5 moles of H2SO4 which would give

2 × 5 × 10–5 = 10 × 10–5 or 1.0 × 10–4 moles of H+ ion in one litre solution.

Therefore,   [H+] = 1.0 × 10–4 mol L–1

         pH = –log[H+] = –log10–4 = –(–4 × log10)

                =–(–4×1)=4

Calculate the pH of 1 × 10–4 molar solution of NaOH.

Solution: NaOH is a strong base and dissociate in its solution as:

        NaOH(aq)  → Na+(aq) + OH(aq)

One mole of NaOH would give one mole of OH ions. Therefore,

  •            [OH] = 1 × 10–4 mol L–1
  •             pOH = –log[OH] = –log × 10–4 = – (–4)
  •                      = 4
  • Since      pH + pOH = 14
  •                pH = 14 – pOH = 14 – 4
  •                       = 10
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