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Posts posted by vrus

  1. I think most Chlorination / Halogenisation reactions need a UV source to initiate the reaction, as it breaks up the Chlorine molecules into Clorine atoms and then allows the Chlorine to bond.


    I know for a fact that the reaction between Chlorine and Hydrogen occurs in presence of sunlight and can produce temperatures in excess of 100 degrees C. Considering that, I suspect the reaction with Propane would be more violent...

  2. I think you could create something that is vaguely similar to water rocket.I just had the thought yesterday night and since I'm on holiday, I'll probably try it out soon myself. Instead of using pressurised water for the rocket's propulsion ...





    use Carbon Dioxide gas. I remember, once in one of my early attempts to carry out fermentation, I had no airlock, no nothing, just a 1 liter water bottle containing sugar solution and some reeeaally pulverizing-stinking yest (I wonder if all yeast is like that ?). The CO2 produced caused the bottle's interiors to increase in pressure and when I opened the cap, it shot out straight upwards (some really quick head-jerking skills needed) and would have travelled quite a bit. I was wondering if a rocket structure with fins and all could be added to it...

    Maybe multi-stage with another smaller bottle inside it that would jettison soon. ( :rolleyes: Hey maybe I should've competed for the X-Prize and all... :cool: ) I'd love any feedback from those who've done it. I recommend adding a large quantities of both reactants, warm water might also help. It might be preferable to carry it out in a fume cupboard for reasons afore mentioned.! :P

  3. Umm.. Cloud are you doing GCSEs?


    Anyway, I think I have the answer for no.2

    I'm a not a great mathematician, but I think I've got the methgod right.


    Let's say that the number of 1p cons = x


    the number of 2p coins = y.




    x + 2y = 502 (1)

    x + y = 374 (2)


    Eliminate x to obtain -

    y = 128.


    Substitute y value into equation to obtain x -

    x + y =374

    x + 128 = 374

    x = 374-128

    x = 246.


    Good luck.

  4. hello people. Long time


    As far as I know, a transformer cannot function without a soft iron core. This is because the e.m.f in the primary coil induces a magnetic field on the iron that then induces an e.m.f in the secondary coil. So I don't see how a transformer could work without that.


    And besides, the loss due to eddy fields and heat, etc. are so small that they are negligible in most cases. Therefore a transformer's efficiency is about 95-98 %. Can someone pls. verify this ?


    So there is no real need for removing the iron core even for efficiency reasons.

  5. Well, there are quite somethings you can do to find out the 'true identity' of this substance!


    (i) If you wanna have some fun and take a bit of risk, then put some of the powder in Mercury Chloride and filter; it should start reacting exothermically with the O2 in the air, as the Mercury Chloride removes Al's oxide layer. I doubt you have this and should take the risk, but just 4 some info :cool:


    (ii) You could mess around with displacement reactions and the sort. Getting an aqueous Mg salt and adding the Al powder to it and doing the same to Zn, Fe, etc (metals lower than Al in reactivity series). It should not displace mg and above, but should displace all those below itself. You know that displacement has occurred when there is a change in colour of the solution or temperature changes.


    (iii) Probably the easiest would be to use QUALITATIVE ANALYSIS.

    Make a salt of a sample of the suspected powder. Then do the following :-


    Add the aqueous Aluminium salt to an equal amount of aqueous NaOH. A white ppt. should form. An excess of the same will have no effect. You should also obtain the same results with Ammonia solution. This should prove it is Aluminium.


    If anybody has any more ideas ideas, please go ahead.. I'm quite interested myself! :embarass:

  6. i had an i-mate smartphone and it had an SD card slot. I used SD cards in it only for listening to songs, using the phone as an mp3 player.


    Once I left the song running and I got a call. The playing stopped and after I answered the call, it wouldn't even detect the songs. I removed it and tried putting it back again like a ... times but nothing happened. Then I removed the card and it worked on my mp3 player. The phone's battery ran out once as I couldn't charge it. When I had the power back on line, the media player worked and also played media after inserting the same SD card.


    That phone is quite messed up though. Got a better one!

  7. hey ppl.

    Had my last mock exams so been "isolated" for a while! I just had to work... But good to be back.


    I just wanted to give my input regarding cold fusion.


    I remember reading about the use of pyroelectric crystals for fusion. I'm not sure if i got it right myself and someone pls. set me right if i am not!


    I think they put this crystal in a hydrogen atmosphere. Then they heated one side and i think the charges in the crystal seperate to alternate sides. Then something was done to induce a spark and fusion occured. Can soebody also explain what that something was? :embarass:

  8. The problem is that inside an internal combustion engine you have reactions going on at VERY high temperatures and VERY high pressures. This causes nitrogen in the air to oxidize and any sulfur in the air to oxidize. This results in the formation of the nitrogen oxides which are the biggest contributor to pollution. You simply can't avoid that formation no matter what you do.


    I've never ever heard of anything like COH2 myself.


    But jdurg, I read somewhere that combustion of Hydrogen purifies the air, as it completes the combustion of NOx and other unburnt hydrocarbons. Will burning hydrogen also create SO2? I thought the sulphur came from the fossil fuel itself and not the atmosphere.... :confused:

  9. I wanted to know how catalysts work. My teachesr just said that it lowers the activation energy of a reaction, so that the bonds are looser, and according to the simple collision theory, molecules are able to have more successful collisions. All this is well, but a little more detail as to how the activation energy is lowered would be helpful. Is there any formula based method or any other that can identify a catalyst for a reaction, or do you haver to find out by trial and error?


    I am under the impression that catalysation has something to do with the catalyst's surface area. If so, for example in the case of the catalytic breakdown of Hydrogen Peroxide, say manganese dioxide is the catalyst, how does the reaction get faster, if the catalyst is settled at the bottom?


    I'd greatly appreciate any help, as if a strange thought or idea arises in my mind, I find it hard to work on topics relating to that...

  10. During hibernation, a hedgehog's body temperature drops to about 5.5 degrees C. Its heart beats between 2 and 6 times a minute and it only takes from 1-3 breaths per minute.


    However the mammal with the lowest body temperature during hiberantion is the hamster with a body temperature of 3.5 degrees C.

  11. Our chemistry teacher did a demonstration recently. He should have done it using Mg(NO3)2, but he felt it was better to use Copper Nitrate for "colour" purposes. It decomposed to give Copper Oxide, Oxygen and Nitrogen Dioxide, which was seperated from the evolved oxygen by dissolving in water to give HNO3 and some HNO2.


    The amount of gas was quite a lot, and considering that Mg(NO3)2 gives the same gas products, I suppose the same would occur. :rolleyes:

  12. Aluminium can be used for electrolysis' date=' but it is not very useful as an electrode for producing a current in a cell. What vrus attempts to do is not electrolysis, but make a cell, which produces some current.


    @vrus: Your electrolyte must have sufficient conductivity. Vinegar only is a weak acid and hardly conducts electricity. The internal resistance of your cell will become very large and make it useless.


    Can't you even get dilute HCl? If you can get that, then you can make a nice cell as follows:



    [*]Dissolve as much as possible of zinc metal in HCl. As a substitute you may simply try a solution of NaCl instead of zinc, dissolved in HCl. That is even more simple and also will do.

    [*]Dissolve as much as possible of copper metal in a HCl/H2O2 mix. Heat the mix for some time to get rid of excess HCl and H2O2.

    [*]Put both solutions in separate beakers.

    [*]Take a flexible tube, fill this with concentrated salt-water and close both ends with cotton-wool (which will be soaked with the salt-solutions). Immerse one end in the beaker with copper-solution and immerse the other end in the beaker with zinc solution.

    [*]Dip a copper plate in the copper solution and dip a zinc plate in the zinc solution. Between the copper and zinc plates you will have a voltage with low internal resistance and that makes your cell nicely powerful.


    Try to go to a hardware store and see if you can find 10% HCl. I hardly can imagine that even such dilute acid cannot be obtained. A solution with 3 to 10% H2O2 should also be available.


    Easy to obtain chemicals might be copper sulfate and zinc oxide for you. They are available at pottery and ceramics stores. With these at hand your copper half-cell can simply be made by dissolving the copper-salt in water. The ZnO can easily be dissolved in dil. HCl.

    As an alternative for HCl you could try to find dilute H2SO4 as the acid in car batteries. With some luck you can obtain that at auto parts suppliers. Yet another nice alternative for HCl is NaHSO4, which is present in many toilet cleaners and also available as pH-minus for swimming pools. You should be capable to find one of these chems as your acid.



    Can I use Na2CO3 instead of NaOH ? Oh and yeah I can get H2O2 @ 6% :D


    I'll check for HCl again... :cool:

  13. I encounetered a problem recently. I used a strong salt solution and magnesium and graphite as electrodes and got the faint glow with the same bulb described before. But then I used Aluminium instead of magnesium and nothing happened. I was expecting it to get brighter, as the difference in reactivity is made larger. Is this because of the Al's oxide layer ?


    I then used a solution of salt, vinegar and some bleach with the same electrodes. But neither worked. Even my LED didn't light up! So I split the volume to make two cells; one with Al and graphite and the Mg and Cu. Still no result... :mad:


    Can someone provide an explanation as to why this is not working and a solution to it ? Great;y appreciate any help in these difficult days ! :P


    (That was my 100th post !!!)

  14. I did a practical in school 2day about electrochemical cells, using a variety of metals and salt solution. I decided to open a thread on how they can be made more efficient, different designs, anamolous finds, etc.


    I come to understand that the larger the difference between the electrodes, the larger the potential difference/ voltage. So we used a Magnesium strip and a graphite rod, giving a voltmeter reading of 1.4 V. I was surprised, as I didn't know it was this easy... :)


    But when I subbed the voltmeter with a filament bulb, there was hardly any effect, except for a very,very, dim glow... :-(


    I think the reason for this was a very low current. So how to increase current ? Decrease Resistance ? How to decrease resistance ? Use a paralell circuit ? Can someone clarify this ?


    My teacher also said that the surface area of the electrode in contact with the electrolyte won't affect the voltage. How is this true? I think this should allow more ions to dissolve, resulting in a larger voltage...


    Would more than one of these cells in series or paralell give a better result ?

    What would be an ideal electrolyte commonly available at home other than aqueous sodium chloride ? :)

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