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Introduction and Basic Concepts
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
A system is said to be in thermodynamic equilibrium if it is in thermal, mechanical, and chemical equilibrium with itself and with the surroundings. Temperature and pressure at all points are the same and there should be no velocity gradient. Systems under temperature and pressure equilibrium but not under chemical equilibrium are sometimes said to be in metastable equilibrium conditions. It is only under thermodynamic equilibrium conditions that the properties of a system can be fixed. Thus for attaining a state of thermodynamic equilibrium, the following three types of equilibrium states must be achieved: (i) Thermal equilibrium: the temperature of the system does not change with time and has the same value at all points of the system. (ii) Mechanical equilibrium: there are no unbalanced forces within the system or between the system and surroundings. The pressure in the system is the same at all points and does not change with respect to time. (iii) Chemical equilibrium: no chemical reaction takes place in the system and the chemical composition, which is the same throughout the system, does not vary with time.
Stoichiometry
Published in Paul Mac Berthouex, Linfield C. Brown, Chemical Processes for Pollution Prevention and Control, 2017
Paul Mac Berthouex, Linfield C. Brown
Stoichiometry is the science of deciphering the qualitative and quantitative information that is given by a balanced stoichiometric equation. A balanced stoichiometric equation shows the chemical composition of the reactants and products and the molar proportions in which they react.
Potential of Equisetum ramosissimum Desf. for remediation of antimony flotation tailings: a case study
Published in International Journal of Phytoremediation, 2019
Dragana Ranđelović, Nevena Mihailović, Slobodan Jovanović
Analyzes were also performed on a scanning electron microscope (SEM, JEOL JSM-6610LV) under high-vacuum conditions, while sample images were obtained using back-scattered electrons (BSE). Fine-grained sample material was coated with a thin layer of gold prior to analysis. Chemical analyzes were made as spot of 5 microns using internal standards on JEOL 6610LV with EDS X-Max Large Area Analytical Silicon Drift (Oxford, England). The chemical composition is presented as the sum of the content of chemical elements given in mass percent (% by weight) and normalized to 100%. The detection limit of the analyzed elements was 0.1 weight %.