Analytical chemistry MLAB 243 Level 4 Lecture time: every WED 8 -10 Lecturer: Ahoud alotibi Email: [email protected].

Analytical chemistry

• MLAB 243• Level 4

• Lecture time: every WED 8 -10• Lecturer: Ahoud alotibi

• Email: [email protected]

• Credits :3 hours (2 +1 )• Course assessment:• 2 mid term exams (30%) + final exam

at the end of the semester (40%)• Continuous assessment (quizzes) 5%• 20% final practical exam + 5% lab

work

• References:• Quantitative Chemical Analysis, 7th

Edition, by Daniel Harris.• Analytical chemistry, 6th Edition by

Gary Christian.• Online resources.

Introduction to the course:

• General chemistry can be divided into :

• organic chemistry• inorganic chemistry • physical chemistry • biochemistry • analytical chemistry

Analytical chemistry:

Definition: it is the science of extraction, identification, and quantitation of an unknown sample. It also deals with methods for determining the chemical composition of samples.

Application of analytical chemistry

• In medicine: analytical chemistry is the basis for clinical laboratory tests which help physicians diagnose disease.

• Industry: analytical chemistry provides the means of testing raw material and assuring the quality of finished products. Such as paints and detergents,etc.

Analytical chemistry plays an important role in nearly all aspects of chemistry. There are many fields that depend on analytical chemistry. For example:

Cont.

• Environmental quality: the air in the cities must be analyzed for detecting carbon monoxide or ocean contamination.

• Forensic analysis: analysis related to crimonology for example; finger print detection and blood analysis.

Analytical chemistry can be divided into two main type:

• Qualitative analysis;An analysis in which we determine the identity of

the constituent in a sample.

• Quantitative analysis;An analysis in which we determine how much of a

constituent is present in a sample.

Quantitative analysis can be divided into:

• Classical chemical analysis:It depends on simple classical technique to determine the

mass, volume. and the corresponding techniques used in this type of analysis are;

Volumetric (measurement in volume).Gravimetric (measurement in mass).

Cont.

• Instrumental analysis:

This analysis depends on the physical properties of the sample where there is no reaction involved . Unlike the classical analysis , instrumental analysis depends on more complex devices such as spectroscopic (interaction of light with matter)and electro analytics (measures electrical potential, resistance, etc) which can help in estimate the sample precisely especially in low concentrations.

Comparing between quantitative and qualitative analysis:• Qualitative Analysis

• Deals with the identification of elements, ions and compounds in a sample (we may be interested in whether a given substance is present or not).

• Quantitative Analysis• Deals with the determination

of how much of one or more constituent is present within a sample.

• There are two kinds of quantitative analysis:1.classical Chemical Analysis

2. Instrumental Analysis

Steps in analytical analysis:

1.Define the problem.

This means that the analysts should know what information is required, the type and amount of sample, the precision and accuracy of the result, the analytical method which can be used to achieve these results, etc.

• precision: describes the reproducibility of a result. If you measure a quantity several times and the values agree closely with each other your measurement is precise.

• Accuracy :describes how close a measured value is to the true value. If a known standard is available accuracy is how close your value is to the known value.

High precision High percision Low percision low percision High accuracy low accuracy high accuracy low accuracy

2. Obtain a representative sample:

A chemical analysis is usually performed on only a small portion of the materiel to be characterized. This portion need to have the same characteristics of the whole sample in order to obtain the actual results.

3. Sample preparation:Most analytical methods requires a liquid form of the sample rather than solid form. Therefore, samples need to be dissolved quantitatively and may also be diluted to the concentration range of the method if they are present in a high concentration.

4.Chemical separation:The sample may contains solutes which interfere with the determination of the analyte. If this is the case, the analyte should be separated from the sample matrix by an acceptable procedure.

5. Perform the measurement :This implies conducting the analytical procedure and collecting the required data.

6. calculation:The final step in the analytical process is to perform the calculation and report the result in an acceptable manner.

Basic tools of analytical chemistry

• In analytical chemistry measurements are made using appropriate instruments or equipment. The array of these equipment is impressive ranging from the simple and inexpensive to the complex and costly. Each instrument has its own purpose of use in the analysis, for example, there are equipment to measure the mass, volume where other are used for transferring solution during an experiment .

Mechanical balance

An object mass is measured using a balance. The most common type is the electronic balance which had replaced the mechanical ones.

Electronic balance

Equipment for measuring the mass:

Equipment for measuring the volume:

• Analytical chemists use a variety of glassware to measure a liquid’s volume. The choice of what type of glassware to use depends on how accurately we need to know the liquid’s volume and whether we are interested in containing or delivering the liquid.

• A graduated cylinder is the simplest device for delivering a known volume of a liquid reagent. The graduated scale allows you to deliver any volume up to the cylinder’s maximum.

cylinder

• Volumetric Pipette: is used to deliver a specified volume of solution. Several styles of pipets are available as shown below.

pipettes

Micro pipettes

Volumetric flask Conical flask

Graduated cylinders and pipets deliver a known volume of solution. A volumetric flask, conical flasks, on the other hand, contains a specific volume of solution

• Burette: used to deliver Variables (in titrations) but known volumes Of solution. It Is graduated long narrow tube with stopcock forDispensing the solution.

.

burette

Measurement with burette:

Washing bottle

funnel

beaker

Thank you