Chemistry Dictionary

In this site we focused on the the areas of science incluod analytical chemisty, general chemistry, inorganic chemistry, organic chemistry, physical chemistry, and spectroscopy.(Online Chemistry Dictionary )

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29.12.20

Activation Energy (delta G)

  2:33 PM    

The diagram shows a system with a metastable state (a), an unstable state (b), and a stable state (c). Energy is required to cause the system to go between these states. The activation energy (DG), for the a-> c process, is (Gb - Ga), that for the c -> a process is (Gb - Gc).


if the system is in contact with a thermal reservoir at a temperature T K, the probability of state (a) acquiring the required activation energy from thermal fluctuations in the system is given by: 
P = exp(- DG/kT) , where k is Boltzmann's constant


Source:
1-Freefullpdf for Scientific Publications
2-Barrett, Nix, and Tetelman,"The Principles of Engineering Materials," Prentice Hall (1973)

   /

Acousto-Optical

  2:21 PM    

Acousto-Optical

An acousto-optical material is one for which the refractive index can be changed by the density fluctuations (strain) produced by an acoustic wave. 

The change in the dielectric constant, el, is related to the mechanical strain, e, through the photoelastic coefficient, p, such that: 

D(1/el ) = pe.

If a longitudinal acoustic wave is sent through an acousto-optically active solid, it establishes a density grating in the material that will diffract a light beam in the manner shown below. The diffracted beam will not be present if there is no acoustic signal (only the transmitted beam will remain) and the device can, therefore, act as an optical switch. 


the table shows some parameters of optoacoustic substances.

Source:
1-Freefullpdf for Scientific Publications
2-Solymar and Walsh, "Lectures on the Electrical Properties of Materials," Oxford Science Publications (1988)

  

28.12.20

Alloy Steels | 4340 Steel

  11:53 AM    

Alloy Steels 

43xx sheets of steel are low alloy steels containing Fe, Ni, Cr, and Mo. 

Alloy Steels | 4340 Steel composition

Fe - 0.4 %C, 0.7 %Mn, 0.2% Si, 1.8%Ni, 0.8% Cr, 0.25% Mo. The alloy may not contain more than 0.04% of either 
Alloy Steels | 4340 Steel


S or P. The material has a tensile strength between 980 and 1960 MPa, the yield stress of 895 to 1570 MPa, and an elongation to fracture between 21 and 11%.


More scientific publications about Alloy Steels | 4340 Steel

   / / /

Aluminum Alloys, 2017-T3, 2024-T2, -T3, -T4

  11:31 AM    

Aluminum Alloy, 2017-T3

Aluminum alloy has copper as its major alloying element and is one of the wrought alloys. 
Aluminum Alloy 2017-T3 contains 
4.0% Cu, 0.7% Mn, 0.6% Mg, 0.5% Si, with the balance being aluminum. 
The T3 heat treatment requires furnace solution heat treatment followed by a quench to room temperature and cold work.
Aluminum Alloy


The Aluminum Alloy has an ultimate tensile strength of about 300 MPa, yield stress in the tension of 165 MPa, and elongation in 50 mm of 27%.

 Aluminum Alloys, 2024-T2, -T3, -T4 

The 2000 series of aluminum alloys have copper as the major alloying element, and the Tn designation is associated with the heat treatment. 
Aluminum Alloy 2024 contains 
The nominal composition is 4.4%Cu, 0.6% Mn, 1.5% Mg, in an aluminum matrix. T2 signifies an alloy that has been cooled from the single-phase condition to room temperature, cold worked, and naturally aged; T3 is an alloy of the same composition that has been furnace solution heat-treated, quenched to room temperature, and cold-worked; for the T4 alloy furnace solution heat treatment is followed by quenching and natural aging.

For 2024-T3: UTS = 485 MPa, Tensile yield stress = 345MPa, 
Elongation in 50 mm = 18%

For 2024-T4: UTS = 470 MPa, Tensile yield stress = 325 MPa, 
Elongation in 50 mm = 20%


More scientific publications about Aluminum Alloy

Source:
1-Freefullpdf for Scientific Publications
2-princeton.edu

   / / / / / /

13.9.18

Theses and dissertations search engine

  6:05 PM    

How can you find the theses and dissertations related to your study?


Dissertations and theses are an important and valuable tool for the library and the student and researcher in all areas of a subject.
Browse millions of science Free PDF articles Papers - Patents - Posters Institutional Repository · peer-reviewed journals · Free download · Open Access

Theses and dissertations search engine 






Free theses and dissertations- free scientific books pdf- free online research papers - free scientific articles pdf Download Free full PDF of Scientific Publications from a lot of scientific resources Physics sciences- Life sciences - Health sciences - Mathematics - Social sciences - Humanities

  

8.11.17

Best chemistry textbook pdf

  6:59 AM    

Best chemistry textbook pdf 

You can download a lot of chemistry textbook from this post, it is easy to download free books of chemistry.
Now you are lucky to find this post because it has a lot of best pdf textbooks of chemistry for free and also you can see it online if you want.


Best chemistry textbook pdf

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Source:
1-Freefullpdf for Scientific Publications

  

2.10.17

Weight percent w/w, w/v, v/v %- Percentage Concentration

  4:14 PM    



Weight percent w/w, w/v, v/v %


weight per weight (W/W), weight per volume (W/V), volume per volume (V/V) meanings and how to use it in chemistry

w/w , w/v, v/v %


These variations on percentage concentration are used in chemistry and biology when making up solutions and have the following meanings.

% w/w
weight per weight: used where the weight of each chemical is used and not the volume (e.g. If I dissolve 10 g of fat in 90 g ethanol so the total mass of the whole solution is 100 g, then I have made a 10% w/w solution of fat)

% w/v
weight per volume: used where a solid chemical is dissolved in a liquid (e.g. if I dissolve 10 g of table salt, sodium chloride, to make up a total volume of 100 mL of a solution then I have made a 10% w/v solution of sodium chloride)

% v/v
volume per volume: used where both chemicals are liquids (e.g. if I dilute 50 mL of acetic acid by adding it to 50 mL of water there is now 50 mL of acetic acid in a total volume of 100 mL, hence the acetic acid concentration is now 50% v/v

% volume per volume (v/v), % weight per volume (w/v) and % weight per weight (w/w)

Source:

Freefullpdf for Scientific Publications

  

Some classes of organic compounds and their functional groups

  12:30 PM    

Some classes of organic compounds and their functional groups

Fifteen of the classes of functional groups are shown, along with the general structural formula associated with that class. The key features are shown in red in the second column

Some classes of organic compounds and their functional groups


Tage: organic chemistry, structural formula, table

Source:
Freefullpdf for Scientific Publications

  

1.10.17

Propane models

  7:42 AM    

Propane models

 Propane, used as a fuel, is shown in 3 different representations commonly used for molecules. Each format is used to convey different information about the structure and components of propane.
Propane models
Propane models


Tage: propane, ball and stick, models, fuel, molecular formula

Source:
Freefullpdf for Scientific Publications

  

Ethane, minor component of natural gas

  7:38 AM    


Ethane, minor component of natural gas

Ethane, a minor component of natural gas, is shown in representations. Each model conveys different information about the structure and components of ethane.


Ethane, minor component of natural gas
Ethane, minor component of natural gas

See also,
Methane Representations

Tage: ethane, natural gas, ball, and stick, model, molecular formula
Source:
Freefullpdf for Scientific Publications

  

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