scholarly journals Implementing of a worksheet related to physical and chemical change concepts

2010 ◽  
Vol 2 (2) ◽  
pp. 733-738 ◽  
Author(s):  
Zeynep Bak Kibar ◽  
Alipaşa Ayas
Keyword(s):  
Chemical Change ◽  
Physical And Chemical

Granite Weathering

2006 ◽  
Author(s):  
Piotr Migon
Keyword(s):  
Solid Rock ◽  
Chemical Change ◽  
Transitional Zone ◽  
Sufficient Evidence ◽  
Small Scale ◽  
Bare Rock ◽  
Moisture Deficit ◽  
Geomorphic Features ◽  
Drying Up ◽  
Physical And Chemical

Weathering is a necessary precursor for landform development. However, in the context of granite it acquires a particular importance for various reasons. First, many granite terrains show an extensive development of deep weathering profiles, which can be extremely varied in terms of their depth, vertical zonation, degree of rock decomposition, and mineralogical and chemical change. Moreover, the transitional zone between the weathering mantle and the solid rock, for which the term ‘weathering front’ is used (Mabbutt, 1961b), may be very thin. There is now sufficient evidence that many geomorphic features of granite landscapes, including boulders, domes, and plains, have been sculpted at the solid rock/weathering mantle interface and they are essentially elements of an exposed weathering front. Therefore, the origin of granite landscapes cannot be satisfactorily explained and understood without a proper understanding of the phenomenon of deep weathering. Second, granites break down via a range of weathering mechanisms, both physical and chemical, which interact to produce an extreme diversity of small-scale surface features and minor landforms. In this respect, it is only limestones and some sandstones which show a similar wealth of weathering-related surface phenomena. Third, both superficial and deep weathering of granite act very selectively, exploiting a variety of structural and textural features, including fractures, microfractures, veins, enclaves, and textural inhomogeneities. In effect, the patterns of rock breakdown may differ very much between adjacent localities, and so the resultant landforms differ. In the context of deep weathering, selectivity is evident in significant changes of profile thickness and its properties over short distances, and in the presence of unweathered compartments (corestones) within an altered rock mass. Fourth, it is emphasized that granites are particularly sensitive to the amount of moisture in the environment (Bremer, 1971; Twidale, 1982). They alter very fast in moist environments, whereas moisture deficit enhances rock resistance and makes it very durable. Hence, a bare rock slope shedding rainwater and drying up quickly after rain will be very much immune to weathering, whereas at its foot a surplus of moisture will accelerate decomposition.

Analytical Methodology from Lavoisier to Mendeleev

2014 ◽  
Author(s):  
Marco Fontani ◽  
Mariagrazia Costa ◽  
Mary Virginia Orna
Keyword(s):  
Chemical Change ◽  
Chemical Properties ◽  
Professional Activity ◽  
Analytical Methodology ◽  
Long Run ◽  
Similar Chemical ◽  
Experimental Errors ◽  
Ancient Times ◽  
Almost All ◽  
Physical And Chemical

Within the period covered by Part II, 1789–1869, 37 true elements, almost all of them metals, were discovered. Prior to this time, about 14 metals had been discovered, excluding those that had been known from ancient times. The discovery of the elements during this period of interest is intimately related to the analytical methodologies available to chemists, as well as to a growing consciousness of just what an element is. Because these methods were also available to the less competent who may have lacked the skills to use them or the knowledge to interpret their results, their use also led to as many, if not more, erroneous discoveries in the same period. One can number among the major sources of error faulty interpretation of experimental data, the “rediscovery” of an already known element, sample impurities, very similar chemical properties (as in the case of the rare earths), the presence of an element in nature in very scarce or trace amounts, gross experimental errors, confusion of oxides and earths with their metals, and baseless dogmatic pronouncements by known “authorities” in the field. Antoine Laurent Lavoisier’s conceptualization of what constitutes an element was a radical break from the principles of alchemy. His stipulation that an element is a substance that cannot be further decomposed conferred an operational, pragmatic, concrete definition on what had previously been a more abstract concept. At the other end of the spectrum was the intuition of Dmitri Mendeleev who, contrary to the prevailing acceptance of Lavoisier’s concept, stressed the importance of retaining a more abstract, more fundamental sense of an element—an idea that in the long run enabled the development of the periodic table. What both men had in common is that they defined and named individual elements as those components of substances that could survive chemical change and whose presence in compounds could explain their physical and chemical properties. Mendeleev’s table has been immortalized in every chemistry classroom—and also concretely in Saint Petersburg, the city that saw most of his professional activity, by a spectacular building-sized model The analytical chemist depends on both of these concepts and indeed, analytical practice preceded Lavoisier’s concept by at least a century.

Physical and chemical change in textbooks: An initial view

1996 ◽  
Vol 26 (1) ◽  
pp. 129-140 ◽  
Author(s):  
Bill Palmer ◽  
David F Treagust
Keyword(s):  
Chemical Change ◽  
Physical And Chemical

Hematological Parameter of Heteropneustes fossilis (Shing fish)

2013 ◽  
Vol 11 (1) ◽  
pp. 3-10
Author(s):  
Tahmina Khanam ◽  
Gulshan Ara Latifa
Keyword(s):  
Chemical Change ◽  
Activity Level ◽  
Hematological Parameter ◽  
Haematological Parameter ◽  
Heteropneustes Fossilis ◽  
Diagnostic Laboratory ◽  
Physiological Conditions ◽  
Erythrocyte Sedimentation ◽  
Specific Variation ◽  
Physical And Chemical

Background: The physiological conditions of fish are essential for the successful fish culture. Objective: The purpose of the present study was to see the haematological parameter of air breathing cat fish (Heteropneustes fossilis) of Bangladesh. Methodology: This animal study was conducted in the “Bargen lab” in the Department of Zoology at University of Dhaka as well as in “The Peoples Pathological lab” which was a private diagnostic laboratory at Dhaka city from July’ 2008 to April’ 2009 for a period of 9(nine) months. The fish was Heteropneustes fossilis. Haemocytometer including two graduated pipettes was used for counting leucocytes. Result: The result indicated eight types of blood cells in peripheral condition of Heteropneustes fossilis. The average cellular counts of Heteropneustes fossilis were erythrocytes 8.45´106 m3, leukocytes 15.44´103m-3, Thrombocytes 34.72%, large lymphocytes 1.02%, small lymphocytes 26.7%, monocyte 3.9%, neutrophil 16.9%, eosinophils 6.97%, basophiles 8.6%, haemoglobin 11.7g 100ml1, erythrocyte sedimentation rate (ESR) 6.49g 100ml-1.  The most of the hematological parameter showed intra specific variation except eosinophils and ESR of Heteropneustes fossilis (Shing fish). Conclusion: Hematological studies shows that the  physiology of  fish  change  with the change in  the environment, time, season, maturity, nutritional state, activity level physical and chemical change in water.DOI: http://dx.doi.org/10.3329/jsf.v11i1.19398

scholarly journals Cathode ray oscillography of gas adsorption phenomena I-A method for measuring high-velocity approach to certain physical and chemical equilibria

1935 ◽  
Vol 151 (873) ◽  
pp. 296-307 ◽  
Author(s):  
M. C. Johnson ◽  
F. A. Vick ◽  
Samuel Walter Johnson Smith
Keyword(s):  
Essential Feature ◽  
Chemical Change ◽  
Optical Methods ◽  
Gas Content ◽  
Time Lags ◽  
Low Velocity ◽  
True Rate ◽  
Reaction Velocity ◽  
Observable Quantity ◽  
Physical And Chemical

The essential feature of many experiments on adsorption, evaporation, surface diffusion, and surface chemistry consists of observing a progress towards equilibrium after altering A the pressure of gas which has access to a solid, or B the temperature of a solid exposed to gas or gas mixture. But such observations only become adequate for investigating probabilities of transition between the relevant physical and chemical states if the true rate of approach to equilibrium is not obscured or distorted by time lags in the experimental methods employed. If the term "reaction velocity" be generalized to include rate of simple phase change, owing to the similarity of the latter to chemical change in its thermodynamic treatment, then the limits to accessible range of such velocity are set by the following: ( a ) the maximum rate at which A or B can be made to stimulate reaction, ( b ) the rate at which resulting energy exchanges affect some observable quantity chosen as indicator, and ( c ) the rate at which the indicator can record itself. Such limitations become serious in the study of reactions occurring in interfacial layers of monomolecular thickness. These present uniquely simple kinetics owing to the elimination of transmission delays in the actual reaction, since all the atoms may be exposed simultaneously to any agency of change; but reaction velocity becomes for that reason so large, in the interesting cases where intrinsic probabilities of transition are not extremely small, that detailed investigation by ordinary means becomes impossible. The difficulty is most acute when the solid surface is reduced to the dimensions of a filament capable of high-temperature flashing, to obey modern needs of reproducible cleanliness; the gas content is then so minute that all optical methods are inapplicable and no micromanometric or thermal observation can keep pace with the reaction. Time constants for the faster of these would seem essentially inaccessible except electron emission from a surface offers an observable quantity indicative of the state of surface layers, and responding instantaneously to any reactions which modify that state. Such thermionic acid photoelectric emission has not hitherto been combined with fast enough recording to take full advantage of this rapidity of response; Langmuir and others have used auxiliary vapours to avoid temperature ranges in which gas reaction would be rapid, while Oliphant and Moon, and Evans, have used mechanical oscillography for alkali ions only, whose behaviour is important in a low-velocity range. The extension which we here put forward, to phenomena rapid enough to justify introducing a cathode ray oscillographic technique, requires firstly certain improvements in the timing, etc., controls of such instruments not needed for their normal use; secondly, it requires theoretical and experimental determinations of the limits imposed on observable velocity by the time taken in attaining pressure equilibria and thermal and electrical steady state, and by the speed of photography. These requirements in establishing the method for rapid surface processes are completed in Part I, in relation to the two standard way A and B of initiating reaction by pressure and temperature. The conclusions are exhibited in photographic examples from phenomena well known but previously inaccessible to exact analysis, before proceeding, Part II, to apply them in the solution of particular problems.

Analysis of the Formation Mechanism of Hollow and Cricoid Stria in Formed Coke

2011 ◽  
Vol 287-290 ◽  
pp. 2927-2932
Author(s):  
Ming Jie Ma ◽  
Quan Run Liu ◽  
Shan Xiu Huang
Keyword(s):  
Heat Conduction ◽  
Chemical Reaction ◽  
Formation Mechanism ◽  
Chemical Change ◽  
Experimental Conditions ◽  
Carbonization Process ◽  
Physical And Chemical

Under certain experimental conditions, the formed coke with hollow and cricoid stria. Through the perfect supposition about briquette carbonization process, the formation mechanism of the hollow and cricoid stria in formed coke is analyzed and the property of physical and chemical change and their conditionality relationship during briquette carbonated are demonstrated by use of the rules of heat conduction, the chemical reaction in the melting stage of colloid matter in coal and hydrodynamics. The conclusions from above analysis has an important instruction for the preparation mechanism of other allied carbon stuff.

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