scholarly journals Induction of Changes in Internal Gas Pressure of Bulky Plant Organs by Temperature Gradients

1990 ◽  
Vol 115 (2) ◽  
pp. 308-312 ◽  
Author(s):  
Kenneth A. Corey ◽  
Zhi-Yi Tan
Keyword(s):  
Bath Temperature ◽  
Ideal Gas ◽  
Gas Pressure ◽  
Temperature Gradients ◽  
Maximum Pressure ◽  
Plant Organs ◽  
Ideal Gas Law ◽  
Increasing Temperature ◽  
Pressure Changes

Water manometers were connected to fruits of tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.), and then fruits were submerged in water baths providing initial temperature gradients between fruit and water of 0 to 19C. Apple (Malus domestics Borkh.) fruits, carrot (Daucus carota L.) roots, witloof chicory (Cichorium intybus L.) roots, rhubarb Rheum rhabarbarum L.) petioles, and pokeweed (Phytolacca americana L.) stems were subjected to water bath temperature gradients of 5C. Internal partial vacuums developed in all organs within minutes of imposing the gradients. The maximum partial vacuums in tomato and pepper fruits increased with increasing temperature gradients. Uptake of water accompanied changes in internal pressure reaching maxima of 17% (w/w) and 2% (w/w) of pepper and tomato fruits, respectively, after 22 hours. Maximum pressure changes achieved in bulky organs deviated from those predicted by the ideal gas law, possibly due to concomitant changes in gas pressure upon replacement of intercellular spaces with water and dissolution of CO2. Partial vacuums also developed in pepper fruits, rhubarb petioles, and pokeweed stems following exposure to air 15C cooler than initial organ temperatures. Results point to the role of temperature gradients in the transport of liquids and gases in plant organs.

scholarly journals The Master Key to the Problem of Reversible Chemical Hydrogen Storage is 12 kJ (mol H2)-1

2021 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Hydrogen Storage ◽  
Storage Capacity ◽  
Ideal Gas ◽  
Equilibrium Thermodynamics ◽  
Ideal Gas Law ◽  
Chemical Hydrogen Storage ◽  
Co Doped ◽  
Normative Role ◽  
The Ideal

<p>This article shows up the intrinsic thermodynamic boundaries to reversible mass transfer on basis of the ideal gas law and classic equilibrium thermodynamics in relation to chemical hydrogen storage. In the event, a global picture of reversible chemical hydrogen storage is unveiled, including an explanation of partial reversibility. The findings of this work help to clarify problems of metal hydride chemistry which otherwise are difficult if not impossible to solve in convergent manner, e.g. why the substitution of 4 mol % Na by K in Ti-doped NaAlH<sub>4</sub> raises the reversible storage capacity by 42 % or the way the dopants take effect in (Rb/K)-co-doped Mg(NH<sub>2</sub>)<sub>2</sub>/2LiH. This work's result is of a wider significance since based on two cornerstones of physical chemistry and particularly for the normative role of hydrogen electrodes to electrochemistry.</p>

scholarly journals The Straightforward Route Towards the Theoretical Specific Free Enthalpy of Electrochemical Reactions

2021 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Ideal Gas ◽  
Electrochemical Reactions ◽  
Free Enthalpy ◽  
Hydrogen Electrode ◽  
Battery Cell ◽  
Faraday’S Law ◽  
Ideal Gas Law ◽  
Sodium Sulfur

<p></p>This paper outlines a simple yet precise method for identifying the theoretical specific free enthalpy of electrochemical reactions on basis of the ideal gas law, equilibrium thermodynamics and Faraday's law, exploiting the normative role of the standard hydrogen electrode in electrochemistry. The result of this approach are discussed in relation to four battery cell reaction examples: LiCoO<sub>2</sub>/C<sub>6</sub>, LiFePO<sub>4</sub>/C<sub>6</sub>, sodium-sulfur (NAS) and NaCl–Ni (ZEBRA). The agreement between calculated and practical values is near-excellent for even stoichiometries which bespeaks the virtually ideal nature of reversible reactions and the quality of the practical optimization efforts alike. These findings highlight the principal nature of intrinsic thermodynamic limitation to equilibrium mass transfer and its key role towards understanding reversible chemical energy storage in a global sense.<br><p></p>

scholarly journals The Master Key to the Problem of Reversible Chemical Hydrogen Storage is 12 kJ (mol H2)-1

2021 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Hydrogen Storage ◽  
Ideal Gas ◽  
Hydrogen Electrode ◽  
Two Phase ◽  
Electrode Potentials ◽  
Ideal Gas Law ◽  
Hydrogen Mass ◽  
Substantial Change ◽  
The Ideal

<p>This article unveils on basis of the ideal gas law, the atomic conception of matter and classic equilibrium thermodynamics the ideal final regularity of reversible hydrogen mass transfer. This result allows to clarify problems of metal hydride chemistry which otherwise are impossible to understand e.g. why the substitution of 4 mol % Na by K in Ti-doped NaAlH<sub>4</sub> raises the reversible hydrogen capacity by 42 % at no substantial change to thermodynamic reaction parameters or how the dopants take effect in (Rb/K)-co-doped Mg(NH<sub>2</sub>)<sub>2</sub>/2LiH; both cases are discussed in this context. This ideal final regularity is a hitherto missed out superposition of physical chemistry fundamentals and defines the maximum specific energy at distinct conditions: directly for two-phase hydrogen storage methods and indirectly for electrochemical systems due to the normative role of hydrogen electrode potentials.</p>

Making sense of sensemaking: using the sensemaking epistemic game to investigate student discourse during a collaborative gas law activity

2021 ◽  
Author(s):  
Kevin H. Hunter ◽  
Jon-Marc G. Rodriguez ◽  
Nicole M. Becker
Keyword(s):  
Problem Solving ◽  
Conceptual Understanding ◽  
Ideal Gas ◽  
Interactive Simulation ◽  
Structural Components ◽  
Student Discourse ◽  
Coding Scheme ◽  
Making Sense ◽  
Ideal Gas Law ◽  
The Ideal

Beyond students’ ability to manipulate variables and solve problems, chemistry instructors are also interested in students developing a deeper conceptual understanding of chemistry, that is, engaging in the process of sensemaking. The concept of sensemaking transcends problem-solving and focuses on students recognizing a gap in knowledge and working to construct an explanation that resolves this gap, leading them to “make sense” of a concept. Here, we focus on adapting and applying sensemaking as a framework to analyze three groups of students working through a collaborative gas law activity. The activity was designed around the learning cycle to aid students in constructing the ideal gas law using an interactive simulation. For this analysis, we characterized student discourse using the structural components of the sensemaking epistemic game using a deductive coding scheme. Next, we further analyzed students’ epistemic form by assessing features of the activity and student discourse related to sensemaking: whether the question was framed in a real-world context, the extent of student engagement in robust explanation building, and analysis of written scientific explanations. Our work provides further insight regarding the application and use of the sensemaking framework for analyzing students’ problem solving by providing a framework for inferring the depth with which students engage in the process of sensemaking.

scholarly journals Experimental investigations of CO2 seepage behaviorin naturally fractured coal under hydro-thermal-mechanical conditions

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4651-4658
Author(s):  
Teng Teng ◽  
Xiaoyan Zhu ◽  
Yu-Ming Wang ◽  
Chao-Yang Ren
Keyword(s):  
Gas Flow ◽  
Confining Pressure ◽  
Gas Pressure ◽  
Experimental Investigations ◽  
Permeability Evolution ◽  
Coal Permeability ◽  
Naturally Fractured ◽  
Series Of Experiments ◽  
Fractured Coal ◽  
Increasing Temperature

Gas-flow in coal or rock is hypersensitive to the changes of temperature, confin?ing pressure and gas pressure. This paper implemented a series of experiments to observe the seepage behavior, especially the permeability evolution of CO2 in naturally fractured coal sample under coupled hydro-thermal-mechanical conditions. The experimental results show that coal permeability increases exponentially with the increasing gas pressure, and tends to be linear when the confining pressure is high. Coal permeability decreases exponentially with the increasing confining pressure. Coal permeability decreases with the increasing temperature generally, but it may bounce up when the temperature rises to high. The results provide reference for the projects of coal gas extraction and carbon dioxide geological sequestration.

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