sorin

Van de Graaff device and common sense in physics …. The working principle for Van de Graaff device is analyzed again in this material: http://elkadot.com/index.php/en/books/electromagnetism/van-de-graaff-device The actual explanation contradicts all we know about triboelectricity. It is impossible for the same belt to come into contact with two identical rollers and to deliver a positive charge to a sphere and a negative charge to another sphere. Either triboelectric series, either actual explanation for VDG device is nonsense. More than that, it is impossible to transfer a same type of charge from a body carrying a smaller charge to another body carrying a greater charge. Therefore the maximum charge accumulated on spheres should be equal with amount of charge generated in contact or friction process. Actual physics it is not able to explain how is possible to accumulate a huge charge on the sphere during belt rotation in contradiction with all known concepts of physics. The Van de Graaff device with a charge injection system does not need any comment. Why don’t we inject directly the charge over the sphere and arrive to billions of volts and it is preferred to inject it on a belt and carried further by the belt…..? The old material is still available as pdf file on the site and in fact the new material is only a refined presentation of it. Best regards, Sorin Cosofret

Hi Strange, Of course I have heard about their different potential electrodes ( in fact there is a new experiment with electrod potential and electrochemistry). If they are different doeas not change the situation.. both metals got oxidised and an electric current flows between. Hi John, Thank you for the link .. but I was prefering some treateses of physical chemistry ... The information there, at least for me is more then well known ... But I havent found anything about local action on that page. The concept is in any case well known to me ... though without relevance for the experiment.

Hi John, There are no 2 cells. Neither Cu or graphite react with water, or graphite with water or acid solution in Zn compartment. If there is a cell between graphite and copper .... what is the main reaction? On the other hand I know enough what I am do because I have a Ph. D in exact sciences... so for you it will be dedicated the next experiment which is more expensive and isotopes....Electrod potential cut off experiment ,,

Hi Enthalpy, Your comment is reasonable but do not explain the situation ... Both electrodes are consumed, hidrogen develops at both electrodes... So there it is a simple guess with no solution for actual chemsitry: Fe = Fe 2+ plus 2e which remains on the metalic electrode Zn = Zn2+ plus 2e which remains on the metalic electrod. According to actual chemistry electrones from Fe must travel at Zn electrode to develop hydrogen and electrons from Zn must travel to Fe electrode to generate hydrogen. How these electrons travel in opposite directions? No answer... So ... there remains the posibility that electrons from Fe react at the Fe electrode with hidrogen cation and form molecular hydrogen and electrons from Zn react at surface of Zn electrode and form molecular hydrogen ... But in this case no charge is goind into extranal circuit so no electric current ... Of course the speed of these reactions are different... but eeven in this case ... I do not think Zn electrones forces Fe electronse to stay cramped ... And this post is only the warming up ... see the covalent compound substituting a ionic salt experiment ...

A simple experiment is proposed below: The ,,positive” electrode is formed by a Cu piece inserted into a glass of water (or a CuSO4 solution). The ,,negative” electrode is formed by a Zn piece inserted into water or into an acid solution (vinegar, citric or sulfuric acid). Vinegar and citric acid are commonly used in food preparation so it is not a big deal to find them. For a more spectacular visual effect, a solution of sulfuric acid, 3 up to 5M can be used in Zn electrode chamber. Common tap water can be used. Of course for more elaborated experiments or for the skeptics deionised water is necessary; for home experiments this can be bought from a car shop. As salt bridge, a covalent compound (graphite) or a metal which does not react with electrolytes (Pt, Au) is used. For graphite, it is possible to arrange a geometrical form in a U shape only from graphite components, or to use two pieces of graphite connected with a metallic conductor. For the simplest setup, two graphite electrodes recovered from used batteries are used. Two graphite pieces recovered from a pen are another available option. With this set up, an electric current of about 30 μA is counted on the ammeter when in the Zn electrode chamber, water is used. After long time of working, the Zn electrode is consumed, and at Cu electrode no visual modifications are observed. An electric current of about 50 μA is counted on the ammeter, when in the Zn electrode chamber, vinegar is used as electrolyte. After long time of working, the Zn electrode is consumed, and at Cu electrode no visual modifications are observed. Bubbles of hydrogen develop on Zn electrode. An electric current from 50 μA up to 5 mA is counted on the ammeter, when in the Zn electrode chamber, a sulfuric acid on growing concentration is used as electrolyte. When sulfuric acid is used, at Zn electrode it can be clearly observed the release of hydrogen gas simultaneously with rapid Zn electrode consume (fig. 4). Formed ZnSO4 gives opalescence in the compartment and starts to sediment when quantity produced is greater then its solubility. At Cu electrode no visual effects are observed. You can find the details of the experiment at http://www.elkadot.com under basics of physical chemistry book. As can be observed in this simple battery, both ,,oxidation” and ,,reduction” phenomena take place at the same electrode (Zn electrode), and, in the same time, a electric current is counted in external circuit. Secondary, a non ionic salt bridge is used so again, the ions movement as explanation for charge compensation does not need any comment. The framework for the conversion of chemical energy in electric energy is completely changed

An unusual battery is proposed in the experiment below. The particularity of this cell is the fact that both electrodes (formal cathode and anode) undergo oxidation phenomenon. The experiment is very simple: put a piece of Fe and a piece of Zn in a sulfuric acid solution and connect these pieces of metal to an ammeter. Although both metals are oxidized, an electric current is generated in an external circuit. The detailed description of the experiment is presented at www.elkadot.com A video is posted too, showing that bubbles of hydrogen develop at both metallic electrodes. It cannot be accepted that electrons are generated at both electrodes and these electrons are traveling in the external circuit in opposite directions only for the sake of traveling...meet each other, greet each other and continues on ... In the frame of actual science, no possible explanation can be formulated for the experiment and a new frame for conversion of chemical energy in electrical energy have to be proposed. You can perform the experiment in the kitchen using same metals and a acetic acid solution (vinegar). Regards,