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Hydronium I UPAC name oxonium Othe

Hydronium I UPAC name oxonium Other names hydronium ion (obsolete) Properties Molecular formula H3O+ Molar mass 19.02 g/mol Acidity (pKa) -1.7 Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references In chemistry, hydronium is the name for the cation H3O+ derived from protonation of water. It is the simplest type of an oxonium ion. Contents [hide] 1 Nomenclature 2 Acids and acidity 3 Solvation 4 Solid oxonium salts 5 References [edit] Nomenclature According to IUPAC nomenclature of organic chemistry, the hydronium ion should be referred to as oxonium. Hydroxonium may also be used unambiguously to identify it. The updated IUPAC nomenclature also recommends the use of oxonium and oxidanium in organic and inorganic chemistry contexts (in particular it states NO hydronium). An oxonium ion is any ion with a trivalent oxygen cation. For example, a protonated hydroxyl group is an oxonium ion, but not a hydronium. It should be written OH3+. [edit] Acids and acidity Oxonium is the cation that forms from water in the presence of hydrogen ions. These hydrons do not exist in a free state: they are extremely reactive and are solvated by water, by forming a covalent bond. An acid is generally the source of these hydrons; however, since water can behave as both an acid and a base, oxoniums exist even in pure water. This special case of water reacting with water to produce oxonium (and hydroxide) ions is commonly known as the self-ionization of water. The resulting oxonium cations are few and short-lived. Despite their short life they form the basis for determining the pH of basic aqueous solutions, since the less there are of these autoionized oxoniums, the more there is base. Oxonium is very acidic: at 25 °C, its pKa is -1.7. It is also the most acidic species that can exist in water (assuming sufficient water for dissolution): any stronger acid will ionize and protonate a water molecule to form oxonium. The acidity of oxonium is the implicit standard used to judge the strength of an acid in water: strong acids must be better proton donors than oxonium, otherwise a significant portion of acid will exist in a non-ionized state. Unlike the oxonium that results from water's autodissociation, these oxonium ions are long-lasting and concentrated, in proportion to the strength of the dissolved acid. The pH of a solution is a measure of its hydrogen ion concentration. Since free protons react with water to form oxonium cation, the acidity of an aqueous solution is determined by its oxonium concentration. [edit] Solvation Researchers have yet to fully characterize the solvation of oxonium cation in water, in part because many different meanings of solvation exist. A freezing-point depression study determined that the mean hydration ion in cold water is approximately H3O+(H2O)6 [1]: on average, each oxonium cation is solvated by 6 water molecules which are unable to solvate other solute molecules. Some hydration structures are quite large: the H3O+(H2O)20 magic ion number structure (called magic because of its increased stability with respect to hydration structures involving a comparable number of water molecules) might place the oxonium inside a dodecahedral cage [2]. However, more recent ab initio molecular dynamics simulations have shown that, on average, the hydrated proton resides on the surface of the H3O+(H2O)20 cluster[3]. Further, several disparate features of these simulations agree with their experimental counterparts suggesting an alternative interpretation of the experimental results. Zundel cationTwo other well-known structures are the Zundel cations and Eigen cations. The Eigen solvation structure has the oxonium ion at the center of an H9O4+ complex in which the oxonium is strongly hydrogen-bonded to 3 neighbouring water molecules [4]. In the Zundel H5O2+ complex the proton is shared equally by two water molecules [5]. Recent work indicates that both of these complexes represent ideal structures in a more general hydrogen bond network defect [6]. Isolation of the oxonium ion monomer in liquid phase was achieved in a nonaqueous, low nucleophilicity superacid solution (HF-SbF5SO2). The ion was characterized by high resolution O-17 nuclear magnetic resonance.[7]. In 2007, Markovitch & Agmon have calculated for the first time ever the enthalpies and free energies of the various hydrogen bonds around the hydronium cation in liquid protonated water[8] at room temperature and discussed the implementation for the proton hopping mechanism. Using molecular dynamics they were able to show that the hydrogen-bonds around the hydronium ion (formed with the three water ligands in the first solvation shell of the hydronium) are quite strong compared to those of bulk water. [edit] Solid oxonium salts For many strong acids, it is possible to form crystals of their oxonium salt that are relatively stable. Sometimes these salts are called acid monohydrates. As a rule, any acid with an ionization constant of 109 or higher may do this. Acids whose ionization constant is below 109 generally cannot form stable H3O+ salts. For example, hydrochloric acid has an ionization constant of 107, and mixtures with water at all proportions are liquid at room temperature. However, perchloric acid has an ionization constant of 1010, and if liquid anhydrous perchloric acid and water are combined in a 1:1 molar ratio, solid oxonium perchlorate forms. The oxonium cation also forms stable compounds with the carborane superacid H(CB11H(CH3)5Br6) [9]. X-ray crystallography shows a C3v symmetry for the oxonium ion with each proton interacting with a bromine atom each from three carborane anions 320 pm apart on average. The [H3O][H(CB11HCl11)] salt is also soluble in benzene. In crystals grown from a benzene solution the solvent co-crystallizes and a H3O.(benzene)3 cation is completely separated from the anion. In the cation three benzene molecules surround oxonium forming pi-cation interactions with the hydrogen atoms. The closest (nonbonding) approach of the anion at chlorine to the cation at oxygen is 348 pm. [edit] References ^ Zavitsas, A. A. (2001) Properties of water solutions of electrolytes and nonelectrolytes. J. Phys. Chem. B 105 7805-7815. ^ Hulthe, G.; Stenhagen, G.; Wennerström, O. & C-H. Ottosson, C-H. (1997) Water cluster studied by electrospray mass spectrometry. J. Chromatogr. A 512 155-165. ^ Iyengar, S. S. ;Petersen, M. K.; Burnham, C. J.; Day, T. J. F.; Voth, G. A. (2005) The Properties of Ion-Water Clusters. I. The Protonated 21-Water Cluster. J. Chem. Phys. 123 084309. ^ Zundel, G. & Metzger, H. (1968) Energiebänder der tunnelnden Überschuß-Protonen in flüssigen Säuren. Eine IR-spektroskopische Untersuchung der Natur der Gruppierungen H5O2+ Z. Phys. Chem. 58 225-245. ^ Wicke, E.; Eigen, M. & Ackermann, Th. (1954) Über den Zustand des Protons (Hydroniumions) in wäßriger Lösung. Z. Phys. Chem. 1 340-364. ^ Marx, D.; Tuckerman, M. E.; Hutter, J. & Parrinello, M. (1999) The nature of the hydrated excess proton in water. Nature 397 601-604. ^ Mateescu, Gheorghe D. & Benedikt, George M. (1979) Water and related systems. 1. The hydronium ion (H3O+). Preparation and characterization by high resolution oxygen-17 nuclear magnetic resonance. Journal of the American Chemical Society , 101(14), 3959-60. ^ Structure and energetics of the hydronium hydration shells. Omer Markovitch and Noam Agmon J. Phys. Chem. A; 2007; 111(12) pp 2253 - 2256; [1] ^ The Nature of the H3O+ Hydronium Ion in Benzene and Chlorinated Hydrocarbon Solvents. Conditions of Existence and Reinterpretation of Infrared Data Evgenii S. Stoyanov, Kee-Chan Kim, and Christopher A. Reed J. Am. Chem. Soc.; 2006; 128(6) pp 1948 - 1958; Abstract Retrieved from "http://en.wikipedia.org/wiki/Hydronium" Categories: Acids | Cations | Water chemistry Views Article Discussion Edit this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Interaction About Wikipedia Community portal Recent changes Contact Wikipedia Donate to Wikipedia Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages Dansk Deutsch Español Français ??? ????? Italiano ?????????? Nederlands ??? Polski Português ??????? ?? Svenska This page was last modified on 19 July 2008, at 02:07. 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This is the html version of the file http://psy.nccu.edu.tw/~bio/Biopsy08_Ch03.ppt. Google automatically generates html versions of documents as we crawl the web. 3 Neurophysiology:The Generation, Transmission, and Integration of Neural Signals 3 Neurophysiology: The Generation, Transmission, and Integration of Neural Signals * Electrical Signals are the Vocabulary of the Nervous System * The Sequence of Transmission Processes at Chemical Synapses * Neurons and Synapses Combine to Make Circuits * Gross Electrical Activity of the Human Brain 3 Electrical Signals Are the Vocabulary of the Nervous System A neuron at rest is a balance of electrochemical forces. Ions – electrically charged molecules, anions are negatively charged and cations are positively charged Ions are dissolved in intracellular fluid, separated from the extracellular fluid by the cell membrane. 3 Electrical Signals Are the Vocabulary of the Nervous System A microelectrode inserted into a resting cell shows that it is more negative than the extracellular fluid. The resting membrane potential is –50 to –80 millivolts (mV) and shows the negative polarity of the cell’s interior. Figure 3.1 Measuring the Resting Potential 3 Electrical Signals Are the Vocabulary of the Nervous System The cell membrane is a lipid bilayer, with two layers of lipid molecules. Ion channels are proteins that span the membrane and allow ions to pass: * gated channels – open and close in response to voltage changes, chemicals, or mechanical action 3 Electrical Signals Are the Vocabulary of the Nervous System Some channels are open all the time and allow only potassium ions (K+) to cross. The neuron shows selective permeability to (K+) – it can enter or leave the cell freely. 3 Electrical Signals Are the Vocabulary of the Nervous System Two opposing forces drive ion movement: * Diffusion causes ions to flow from areas of high to low concentration, along their concentration gradient. * Electrostatic pressure causes ions to flow towards oppositely charged areas. Figure 3.2 Ionic Forces Underlying Electrical Signaling in Neurons 3 Electrical Signals Are the Vocabulary of the Nervous System At rest, K+ ions move into the negative interior of the cell because of electrostatic pressure. As K+ ions build up inside the cell, they also diffuse out along the concentration gradient. 3 Electrical Signals Are the Vocabulary of the Nervous System K+ reaches equilibrium when the movement out is balanced by the movement in. This corresponds to the resting membrane potential of about –60 mV. Figure 3.3 The Ionic Basis of the Resting Potential (Part 1) 3 Electrical Signals Are the Vocabulary of the Nervous System The Nernst equation describes the voltage produced when a membrane separates different concentrations of ions. The membrane is also slightly permeable to sodium ions (Na+) and ions leak in. The sodium potassium pump pumps Na+ out and K+ in, to maintain the resting potential. Figure 3.3 The Ionic Basis of the Resting Potential (Part 2) Figure 3.4 The Distribution of Ions Inside and Outside of a Neuron 3 Electrical Signals Are the Vocabulary of the Nervous System Action potentials, or nerve impulses, are brief but large changes in membrane potential. They originate in the axon hillock and are propagated along the axon. Patterns of action potentials carry information to postsynaptic targets. 3 Electrical Signals Are the Vocabulary of the Nervous System Hyperpolarization is an increase in membrane potential, caused by inhibitory messages, which puts it farther away from zero. Depolarization is a decrease in membrane potential caused by excitatory messages, bringing it closer to zero. 3 Electrical Signals Are the Vocabulary of the Nervous System A graded response is a postsynaptic change in electrical potential that spreads passively across the membrane, and decreases over time and distance. A hyperpolarizing stimulus produces a response that has the same shape as the stimulus: * The greater the stimulus the greater the response 3 Electrical Signals Are the Vocabulary of the Nervous System Local potentials - also called graded or postsynaptic potentials As a local potential spreads across the membrane, it diminishes as it moves away from the point of stimulation. Figure 3.5 The Effects of Hyperpolarizing and Depolarizing Stimuli on a Neuron (Part 1) 3 Electrical Signals Are the Vocabulary of the Nervous System A depolarizing stimulus is the same as a hyperpolarizing one, to a point. If the membrane reaches the threshold – about –40 mV – it triggers an action potential. The membrane potential reverses and the inside of the cell becomes positive. Figure 3.5 The Effects of Hyperpolarizing and Depolarizing Stimuli on a Neuron (Part 2) 3 Electrical Signals Are the Vocabulary of the Nervous System All-or-none property of action potentials: the neuron fires at full amplitude or not at all – does not reflect increased stimulus strength Action potentials increase frequency with increased stimulus strength. Afterpotentials – follow action potentials 3 Electrical Signals Are the Vocabulary of the Nervous System Action potentials are produced by the movement of Na+ ions into the cell. At the peak the concentration gradient pushing Na+ ions in equals the positive charge driving them out. Membrane shifts briefly from a resting state to an active state, and back. 3 Electrical Signals Are the Vocabulary of the Nervous System Voltage-gated Na+ channels open in response to the initial depolarization. More voltage-gated channels open and more Na+ ions enter. This continues until the membrane potential reaches the Na+ equilibrium potential of +40 mV. 3 Electrical Signals Are the Vocabulary of the Nervous System As the inside of the cell becomes more positive, voltage-gated K+ channels open. K+ moves out and the resting potential is restored. Figure 3.6 Mediation of the Action Potential by Voltage-Gated Sodium Channels 3 Electrical Signals Are the Vocabulary of the Nervous System Refractory period – only some stimuli can produce an action potential Absolute refractory phase – no action potentials are produced Relative refractory phase – only strong stimulation can produce an action potential 3 Electrical Signals Are the Vocabulary of the Nervous System Ion channels are very specific in their function: K+ channels are lined with oxygen atoms that mimic water molecules. K+ ions pass through this selectivity filter more easily than Na+ Channelopathy – genetic abnormality of ion channels Box 3.1 (A) Changing the Channel 3 Electrical Signals Are the Vocabulary of the Nervous System Animal toxins selectively block certain channels: * Tetrodotoxin (TTX) and saxitoxin (STX) block voltage-gated Na+ channels. * Batrachotoxin forces Na+ channels to stay open. Box 3.1 (B) Changing the Channel 3 Electrical Signals Are the Vocabulary of the Nervous System Action potentials are regenerated along the axon – each adjacent section is depolarized and a new action potential occurs. Action potentials travel in one direction because of the refractory state of the membrane after a depolarization. Figure 3.7 Propagation of the Action Potential 3 Electrical Signals Are the Vocabulary of the Nervous System Conduction velocity – the speed of action potentials – varies with diameter Nodes of Ranvier – small gaps in the insulating myelin sheath Saltatory conduction – the axon potential travels inside the axon and jumps from node to node Figure 3.8 Conduction along Unmyelinated versus Myelinated Axons (Part 1) Figure 3.8 Conduction along Unmyelinated versus Myelinated Axons (Part 2) 3 Electrical Signals Are the Vocabulary of the Nervous System Synapses cause local changes in postsynaptic membrane potentials, through neurotransmitters. Besides chemical synapses there are electrical synapses, or gap junctions. Ions flow directly through large channels into adjacent cells, with no time delay. Box 3.2 (A) Electrical Synapses Work with No Time Delay Box 3.2 (B) Electrical Synapses Work with No Time Delay 3 Electrical Signals Are the Vocabulary of the Nervous System Postsynaptic potentials are brief changes in the resting potential. Excitatory postsynaptic potential (EPSP) – produces a small local depolarization, pushing the cell closer to threshold Synaptic delay – the delay between an action potential reaching the axon terminal and creating a postsynaptic potential 3 Electrical Signals Are the Vocabulary of the Nervous System Inhibitory postsynaptic potential (IPSP) – produces a small hyperpolarization, pushing the cell further away from threshold IPSPs result from chloride ions (Cl-) entering the cell, making the inside more negative. Figure 3.9 Recording Postsynaptic Potentials 3 Electrical Signals Are the Vocabulary of the Nervous System Neurons perform information processing to integrate synaptic inputs. A postsynaptic neuron will fire an action potential if a depolarization that exceeds threshold reaches its axon hillock. Figure 3.10 Spatial Summation in a Postsynaptic Cell (Part 1) Figure 3.10 Spatial Summation in a Postsynaptic Cell (Part 2) 3 Electrical Signals Are the Vocabulary of the Nervous System Spatial summation is the summing of potentials that come from different parts of the cell. If the overall sum – of EPSPs and IPSPs – can depolarize the cell at the axon hillock, an action potential will occur. Figure 3.10 Spatial Summation in a Postsynaptic Cell (Part 3) 3 Electrical Signals Are the Vocabulary of the Nervous System Temporal summation is the summing of potentials that arrive at the axon hillock at different times. The closer together in time that they arrive, the greater the summation and possibility of an action potential. 3 The Sequence of Transmission Processes at Chemical Synapses The sequence of transmission: * Action potential travels down the axon to the axon terminal. * Voltage-gated calcium channels open and calcium ions (Ca2+) enter. * Synaptic vesicles fuse with membrane and release transmitter into the cleft. 3 The Sequence of Transmission Processes at Chemical Synapses * Transmitters bind to postsynaptic receptors – cause an EPSP or IPSP. * EPSPs or IPSPs spread toward the postsynaptic axon hillock. * Transmitter is inactivated or removed – action is brief. * Transmitter may be bound by presynaptic autoreceptors, decreasing release. Figure 3.11 Steps in Transmission at a Chemical Synapse 3 The Sequence of Transmission Processes at Chemical Synapses An action potential causes Ca2+ channels to open in the axon terminal and allow Ca2+ into the cell. Ca2+ causes synaptic vesicles to fuse with the presynaptic membrane and release neurotransmitter into the cleft. 3 The Sequence of Transmission Processes at Chemical Synapses Ligands fit receptors and activate or block them: * Endogenous ligands – neurotransmitters and hormones * Exogenous ligands – drugs and toxins from outside the body 3 The Sequence of Transmission Processes at Chemical Synapses A synapse that uses acetylcholine (ACh) has recognition sites for ACh within the receptor molecules in the postsynaptic membrane. ACh can be excitatory, and open channels for Na+ and K+, or inhibitory, and open channels for Cl-. Figure 3.12 A Nicotinic Acetylcholine Receptor 3 The Sequence of Transmission Processes at Chemical Synapses Some chemicals can fit on cholinergic receptors and block the action of ACh: * Curare and bungarotoxin block ACh receptors – are antagonists However, muscarine and nicotine mimic ACh and are agonists of the receptor. 3 The Sequence of Transmission Processes at Chemical Synapses The number of receptors in cells can vary (in plasticity) daily in adulthood - also during development or with drug use. Up-regulation is an increase in the number of receptors, and down-regulation is a decrease. 3 The Sequence of Transmission Processes at Chemical Synapses Receptors control ion channels in two ways: Ionotropic receptors open when bound by a transmitter (also called a ligand-gated ion channel). Metabotropic receptors recognize the transmitter but instead activate G proteins. Figure 3.13 Two Types of Chemical Synapses (Part 1) 3 The Sequence of Transmission Processes at Chemical Synapses G proteins, or first messengers, sometimes open channels or may activate another chemical to affect ion channels. The chemical is known as the second messenger – it amplifies the effects of the G protein and may lead to changes in membrane potential. Figure 3.13 Two Types of Chemical Synapses (Part 2) 3 The Sequence of Transmission Processes at Chemical Synapses Transmitter action is brief: * Degradation is the rapid breakdown and inactivation of transmitter by an enzyme. Example: acetylcholinesterase (AChE) breaks down ACh and recycles it 3 The Sequence of Transmission Processes at Chemical Synapses * Reuptake – transmitter is taken up into the presynaptic cell Pinocytosis is the process of repackaging transmitter into vesicles. Transporters are special presynaptic receptors involved in reuptake. 3 The Sequence of Transmission Processes at Chemical Synapses Types of synapses: Axo-dendritic – axon terminal synapses on a dendrite Axo-axonic - between two axons Dendro-dendritic – between two dendrites Retrograde – uses gas to signal presynaptic cell to release transmitter 3 The Sequence of Transmission Processes at Chemical Synapses Ectopic transmission occurs outside of conventional synapses. Varicosities are axonal swellings where transmitter may diffuse out. These nondirected synapses release transmitter steadily to broad areas. 3 Neurons and Synapses Combine to Make Circuits A neural chain is a simple series of neurons. The knee jerk reflex is a circuit for the stretch reflex, consisting of: * Sensory neuron * Motor neuron * Synapse 3 Neurons and Synapses Combine to Make Circuits The knee jerk reflex is extremely fast: * Axons are myelinated and large * Sensory cells synapse directly onto motoneurons * Uses fast, ionotropic synapses Figure 3.14 The Knee Jerk Reflex (Part 1) Figure 3.14 The Knee Jerk Reflex (Part 2) 3 Neurons and Synapses Combine to Make Circuits The visual system is a circuit with other features: Convergence – many cells send signals to one cell Divergence – one cell send signals to many cells Units are arranged in parallel, and have lateral interaction across units. Figure 3.15 Two Representations of Neural Circuitry (Part 1) Figure 3.15 Two Representations of Neural Circuitry (Part 2) 3 Gross Electrical Activity of the Human Brain An encephalogram (EEG) is a recording of brain potentials, or brain waves. Brain potentials indicate sleep states and provide data in seizure disorders. Figure 3.16 Gross Potentials of the Human Nervous System (Part 1) 3 Gross Electrical Activity of the Human Brain In the normal brain, activity tends to be desynchronized across regions. A symptom of epilepsy is seizure – a synchronization of electrical activity in the brain. The brain wave pattern during seizure is described as epileptiform activity. 3 Gross Electrical Activity of the Human Brain Categories of seizures: Grand mal – abnormal activity throughout the brain * Characteristic movements are tonic and clonic contractions. * Seizure is followed by confusion and sleep. Box 3.3 (A) Seizure Disorders 3 Gross Electrical Activity of the Human Brain Petit mal seizure – brain waves show patterns of seizure activity for 5 to 15 seconds, can be several times a day No unusual muscle activity, except for stopping and staring Events during seizure are not remembered. Box 3.3 (B) Seizure Disorders 3 Gross Electrical Activity of the Human Brain Complex partial seizures – do not involve entire brain Aura – unusual sensation that may precede a seizure Kindling – experimentally inducing a seizure by repeatedly stimulating a brain region Box 3.3 (C) Seizure Disorders 3 Gross Electrical Activity of the Human Brain Event-related potentials (ERPs) are large potential shifts caused by discrete stimuli. Auditory-evoked brainstem potentials are generated in the brainstem, far from the recording site – can be used to detect hearing impairment. Figure 3.16 Gross Potentials of the Human Nervous System (Part 2)

How to reproduce this experiment The

How to reproduce this experiment The CFR project is a High Temperature Plasma Electrolysis fully based on the Tadahiko Mizuno experiment from the university of Hokkaido in Japan. This is a very interesting experiment and its implication can be a real breakthrough in the field of New and Clean energy source.... The enhanced CFR is composed of a 2000 mL thermostatic reaction vessel filled with 800 mL of demineralized water and Potassium Carbonate ( K2CO3 ). The electrolyte solution commonly used is 0.5 molar ( 0.5 M ). There are three temperature probes ( K probe or PT100 ). Two probes are used for measuring the temperature of the cooling water (Temp In and Temp Out ), and one probe is used for measuring the temperature of the electrolyte solution. You need also to use a flowmeter to measure the cooling water flow. The Cathode used is a 4 mm tungsten rod. The tungsten rod can be a pure tungsten rod or a Th-loaded tungsten TIG electrode (WT20) (with thorium oxide ThO2: 1.70% to 2.20% ) commonly used for plasma welding. The use of a Th-loaded rod increases the life of your cathod. The sputtering effect produced by the thermionic emission is lower with a Th-loaded rod than with a pure tungsten rod. The anode used is composed of stainless steel mesh ( a grid ) maintained with stainless steel rods. If you have planned to conduct some chemical analysis, I recommend you to use a grid made with platinum or nickel . All the wires connections are made with a 1.5 mm2 copper flexible wire gained with silicon. To avoid projections of some drops of the electrolyte solution from the CFR during the plasma ignition sequence, I recommend you to put floating balls on the surface of the liquid (hollow floating balls; pp, 20mm, 2000 PK from Cole Parmer Instrument ). Use a DC Power Supply which is able to give about 300 V DC at 20 A ( don't use AC voltage ). The voltage is tuned with an autotransformer Switch on the fume hood, Set the autotransformer to 0 Volt and switch on the power supply, The voltmeter (set on DC) is connected at the input of the CFR cell and the DC current clamp is connected on the positive wire, Turn the knob of the autotransformer so as to get 30V DC on the CFR cell, Let the electrolysis warm up the cell up to 50°C, At 50°C drop the voltage to 0 Volt and switch off the main power supply, Wait 30 sec to exhaust the mixture of hydrogen/oxygen, Measure the temperature ( TSinp ) of the input of the cooling water, Measure the temperature ( TSout ) of the output of the cooling water. Measure the temperature ( Tr_initial ) of the electrolyte then, immediatly, switch on the power supply, Slowly, turn the autotransformer knob so as to get 200 VDC across the cell. Start the chronometer, Note the Voltage and Current values at the permanent regime (pink glow discharge), End the run after ~3 minutes. ( set the voltage to 0 Volt and switch off the power supply ). Stop the chronometer (time). Measure the temperature ( Tr_final ) of the electrolyte, Measure the flow of the cooling water (Flow in L/min), Measure the temperature ( TEinp ) of the input of the cooling water, Measure the temperature ( TEout ) of the output of the cooling water.

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