Analytical chemistry

Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials.

Classical methods

Classical methods

• 1 Qualitative analysis
  • 1.1 Chemical tests
  • 1.2 Flame test
• 2 Quantitative analysis
  • 2.1 Gravimetric analysis
  • 2.2 Volumetric analysis
  • 2.3 Electroanalytical methods
  • 2.4 Spectroscopic methods

Qualitative analysis

A qualitative analysis determines the presence or absence of a particular compound, but not the mass or concentration. By definition, qualitative analyses do not measure quantity.

Quantitative analysis

In analytical chemistry, Quantitiative analysis is the measurements of quantities of substances produced in reactions rather than simply noting the nature of the reactions.

Gravimetric analysis

Gravimetric analysis methods determine the mass of analyte or some compound chemically related to it. In other word, gravimetric analysis is the quantitative analysis process of chemical substances by weight. 

Volumetric analysis

Volumetric analysis is quantitative analysis  of liquids or solutions by comparing the volumes that react with known volumes of standard reagents, usually by titration; in other word, the determination of the concentration by volume of a substance in solution, as by titration.

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SHELL & TUBE HEAT EXCHANGER

SHELL & TUBE HEAT EXCHANGER

Shell and tube heat exchangers are the most widely used type of heat exchanger.

GENERAL INFORMATION

The inside of the exchanger contains many tubes and baffles, as shown in the picture below. These tubes and baffles help direct the two streams flowing through the exchanger.

STRAIGHT TUBE SHELL & TUBE HEAT EXCHENGER

STRAIGHT TUBE SHELL & TUBE HEAT EXCHENGER

A shell and tube heat exchanger consists of several tubes enclosed in a shell. One fluid flows through the tubes while the other fluid is conducted through the shell. Flow through the shell and tubes can be countercurrent, cocurrent, or cross flow. In countercurrent flow, the shell fluid flows in the opposite direction of the tube fluid. In cocurrent flow the shell fluid flows in the same direction as the tube fluid. Lastly, in cross flow the shell fluid flows perpendicular to the flow of the tube fluid. In general, countercurrent flow results in the most efficient heat transfer.

U TUBE SHELL & TUBE HEAT EXCHENGER

The baffles serve two functions: Their strategic positioning supports the tubes, preventing vibration and sagging, and they also channel the fluid in the shell side, resulting in more efficient heat transfer.

U TUBE SHELL & TUBE HEAT EXCHENGER

Static mixers are sometimes placed in the tubes of the shell and tube exchangers to help dissipate heat. Mixing of the fluids in the tube removes temperature, velocity, and material composition gradients. Static mixers also allow fluids to be cooled near their freezing temperature without plugging the tubes.

Static mixer

The diagram below shows the mixing that occurs as the flow in the tube encounters the static mixer. The mixer itself does not move.

Static mixer

ADVANTAGES	DISADVANTAGES
Can handle fluids at high temperatures and pressures. Can handle fluids of all states. Easy to dismantle for cleaning or repairs. Design can be adapted to meet operating conditions.	One unit can only be used for one duty. High amounts of heat loss occur, so insulation is required. Larger space requirements and more expensive than plate and frame. Over time vibrations may damage the heat exchanger. Baffle placement may be optimized to reduce vibrations and help the heat exchanger last longer.

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Plate and Frame Heat Exchanger

PLATE & FRAME

Typically, plate and frame heat exchangers are used for liquid-liquid exchange at low to medium pressures. However, gasket-free plate and frame heat exchangers can safely operate at high temperatures and pressures. Plate and frame heat exchangers offer flexibility because plates can be either added or compressed for each different situation.

Plate and Frame Heat Exchanger

Plate and Frame Heat Exchanger

GENERAL INFORMATION

The gaps between the plates in plate and frame heat exchangers can be adjusted according to the degree of fouling (deposits, corrosion, etc.) that is expected.

Plates of Plate and Frame Heat Exchanger

The counter-current flow of fluids that occurs in plate and frame heat exchangers allows approach temperatures as low as 1 to 2°F.

Gaskets ensure that the cold fluid (blue) and the hot fluid (red) don't mix. Alternatives to the traditional gasket seal include brazing and laser-welding.

The plates are stacked in an alternating manner to cause the counter current flow. The diagram below shows the flow in a heat exchanger. The design allows for the two media to flow in alternate directions and not be mixed. However, heat can be transferred from one medium to the other through the plates. 

ADVANTAGES

DISADVANTAGES

Require less space and are less expensive than shell and tube heat exchangers. Easy to adjust for different liquids by adding or subtracting plates. Pressure can be varied by compressing the plates. One frame can be used for multiple duties by simply changing plates. Working temperatures up to 550°C and pressures of 780 psi are possible with gasket-free versions. High heat transfer coefficients relative to shell and tube heat exchangers. Up to ten times more resistant to fouling than shell and tube heat exchangers.

Gasketed plate and frame heat exchangers have a maximum operating condition of 149°C and 300 psi. Not good for vaporizing fluids or large amounts of vapor. Gasket-free versions are impossible to open for inspection or cleaning.

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Shreve's Chemical Process Industries

Shreve-s-Chemical-Process-Industries DOWNLOAD pdf

Shreve-s-Chemical-Process-Industries

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Top Best Universities for Chemical Engineering

One : Massachusetts Institute of Technology (MIT)

Massachusetts Institute of Technology (MIT)

Entry Requirements (UK):

• Four years of English
• Maths, at least to the level of calculus
• Biology, Chemistry & Physics
• MIT internal exams
• Interview by one of 3000 MIT graduates

Location: Massachusetts, United States

Student Satisfaction: 96%

Undergraduate Female/ Male Ratio:  50% Male, 50% Female

University Website: http://www.mit.edu

Two : University of California, Berkeley (UCB)

North Reading Room at Doe Library at the University of California

Entry Requirements (UK):

• Undergraduate applicants must submit scores on an approved test of mathematics, language arts and writing — either the ACT Plus Writing or the SAT Reasoning Test.

Location: California, United States

Student Satisfaction: 83.8%

Undergraduate Female/ Male Ratio: 47% Male, 53% Female

University Website: http://www.berkeley.edu/index.html

Three: Imperial College London

Imperial College London

Entry Requirements:

• A*AA – A Levels (Math at A* & Chemistry A)

Location: London, United Kingdom

Student Satisfaction: 78%

Undergraduate Female/ Male Ratio: 64% Male, 36% Female

University Website: http://www3.imperial.ac.uk

Four: University of Oxford

University of Oxford

Entry Requirements:

• A*AA (Including Maths & Physics)
• Each applicant must successfully complete interview process.

Location: Oxford, United Kingdom

Student Satisfaction: 93%

Undergraduate Female/ Male Ratio: 47% Male, 53% Female

University Website: http://www.ox.ac.uk

Five : University of Cambridge

University of Cambridge

Entry Requirements:

• Must acquire 4 or 5 AS Levels with AAAA
• At least three A Levels with A*AA
• Each applicant must successfully complete interview process.

Location: Cambridge, United Kingdom

Student Satisfaction: 92%

Undergraduate Female/ Male Ratio: 48% Male, 52% Female

University Website: http://www.cam.ac.uk

Six : The University of Tokyo

The University of Tokyo

Entry Requirements:

• High level of qualifications from College or equivalent (BBB)

Location: Tokyo, Japan

Student Satisfaction: 82%

University Female/ Male Ratio: 80% Male, 20% Female

University Website: http://www.u-tokyo.ac.jp/en/

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Chemistry

Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is chiefly concerned with atoms and molecules and their interactions and transformations, for example, the properties of the chemical bonds formed between atoms to create chemical compounds. As such, chemistry studies the involvement of electrons and various forms of energy in photochemical reactions, oxidation-reduction reactions, changes in phases of matter, and separation of mixtures. Preparation and properties of complex substances, such as alloys, polymers, biological molecules, and pharmaceutical agents are considered in specialized fields of chemistry.

Chemistry is sometimes called the central science because it bridges other natural sciences like physics, geology and biology. Chemistry is a branch of physical science but distinct from physics.

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PROPERTIES OF SOLS

PROPERTIES OF SOLS :

OPTICAL PROPERTIES OF SOLS:    

Sols exhibit Tyndall effect:

When a strong beam of light is passed through a sol and viewed at right angles, the path of light shows up as a hazy beam or cone. This is due to the fact that sol particles absorb light energy and then emit it in all directions in space. This ‘scattering of light’, as it is called, illuminates the path of the beam in the colloidal dispersion.

     The phenomenon of the scattering of light by the sol particles is called Tyndall effect.

The illuminated beam or cone formed by the scattering of light by the sol particles is often

referred as Tyndall beam or Tyndall cone.

            Tyndall effect (Illustration).

Tyndall effect in nature.

KINETIC PROPERTIES OF SOLS:

Brownian Movement: 

     The continuous rapid zig-zag movement executed by a colloidal particle in the dispersion

medium is called Brownian movement or motion.

An illustration of Brownian movement

This motion is independent of the nature of the colloidal particles. It is more rapid when the size of the particles is small and the solution is less viscous.

ELECTRICAL PROPERTIES OF SOLS:

The sol particles carry an electric charge:

The most important property of colloidal

  

dispersions is that all the suspended particles posses either a positive or a negative charge. The mutual forces of repulsion between similarly charged particles prevent them from aggregating and settling under the action of gravity. This gives stability to the sol. The sol particles acquire positive or negative charge by preferential adsorption of positive or negative ions from the dispersion medium. For example, a ferric hydroxide sol particles are positively charged because these adsorb Fe3+ ions from ferric chloride (FeCl3) used in the preparation of the sol. Since the sol as a whole is neutral, the charge on the particle is counterbalanced by oppositely charged ions termed counterions (in this case Cl–) furnished by the electrolyte in medium.

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ULTRAFILTRATION, NANOFILTRATION AND REVERSE OSMOSIS

What is filtration? 

Filtration is a process of removing particulate matter from water by forcing the water through a porous media. This porous media can be natural, in the case of sand, gravel and clay, or it can be a membrane wall made of various materials. Sometimes, large particles are settled before filtration; this is called sedimentation.

What is ultrafiltration? 

An ultrafiltration filter has a pore size around 0.01 micron. A microfiltration filter has a pore size 

around 0.1 micron, so when water undergoes microfiltration, many microorganisms are removed, but viruses remain in the water. Ultrafiltration would remove these larger particles, and may remove some viruses. Neither microfiltration nor ultrafiltration can remove dissolved substances unless they are first adsorbed (with activated carbon) or coagulated (with alum or iron salts). 

MF, UF, NF, RO

What is nanofiltration? 

Nanofiltration is a relatively recent membrane filtration process used most often with low total dissolved solids water such as surface water and fresh groundwater, with the purpose of softening (polyvalent cation removal) and removal of disinfection by-product precursors such as natural organic matter and synthetic organic matter.

NANOFILTRATION (NF) originates in the 1950s, where loose reverse osmosis (RO) or tight ultrafiltration (UF) membranes were used to produce potable water from saline solutions. Today, it has evolved as a membrane technology in its own right, recognising that despite the potential for NF to solve many industrial separation problems, the actual number of uses are limited by the necessity for selectivity and stability flux improvements.

A nanofiltration filter has a pore size around 0.001 micron. Nanofiltration removes most organic molecules, nearly all viruses, most of the natural organic matter and a range of salts. Nanofiltration removes divalent ions, which make water hard, so nanofiltration is often used to soften hard water. 

What is reverse osmosis? 

Reverse osmosis filters have a pore size around 0.0001 micron. After water passes through a 

reverse osmosis filter, it is essentially pure water. In addition to removing all organic molecules 

and viruses, reverse osmosis also removes most minerals that are present in the water. Reverse osmosis removes monovalent ions, which means that it desalinates the water. To understand how reverse osmosis works, it is helpful to understand osmosis.

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What are side products of petroleum distillation?

There are no side products from petroleum distillation.  All parts of a barrel of oil that go through a distillation unit are used to make products.

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Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation.

A chemical reaction is a chemical change which forms new substances.

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Unit operation

In chemical engineering and related fields, a unit operation is a basic step in a process. Unit operations involve a physical change or chemical transformation such as separation, crystallization, evaporation, filtration, polymerization, isomerization, and other reactions. For example, in milk processing, homogenization, pasteurization, chilling, and packaging are each unit operations which are connected to create the overall process.

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Volatility

In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.

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