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About Harry_-

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  1. I was wondering, why do batteries slowly run out over time? I presume in electronics such as a torch that the circuit is broken when unused so why does this occur?
  2. Also I was wanting to let each student do this mini kids version. Here, yeast is the catalyst, does anyone know the exact decomposition reaction which is happening here? https://www.thoughtco.com/kid-friendly-elephant-toothpaste-demo-604164
  3. Attached is my practical proposal. It has a link at the bottom that should explain things. Also here is a youtube link : Elephants Toothpaste Experiment.docx Ok so I have seen these but my plan is to scale it down so each student can have a mini experiment. Also I need to work out the volume I will create as if I make mess my teacher will kille me
  4. Hi, I am in secondary school studying chemistry. I chair the school's STEM society and am wanting to give a talk and practical on the elephants toothpaste that you may have seen online. Elephants toothpaste is large amounts of oxygen trapped in soap. To make a plume of this, you use hydrogen peroxide and a catalyst that releases the oxygen at an increased rate such as potassium Iodide (iodide ions are our catalyst). I am wanting to give this demonstration to other students and need to work out the volume of 'bubbles' that will be made so that I do not make too much. I will be using 100 volumes H2o2 Also I understand volume as a measurement of concentration in this case, however a lot of online sources use percentage. Do I take this as percentage by mass or by volume. Thanks
  5. I am also happy to get away from the electronics :) As for temperature, my maximum resolution is 0.1 kelvin due to equipment av available. Obviously this isn't ideal with my level of precision of voltage but without that precision I wouldn't see any change in voltage and therefore would have no results to show. As for concentration I believe the school's are 5% error, which again isn't great but it will have to do. Unfortunately waste will not be accepted by my teachers and they don't want several dm(3) of solution lying around. I will try and make as large quantities as they will allow (probably 250cm(3) for each electrolyte), using a volumetric flask. Your physical problems are very interesting and I have never come across any of them before. I theorise with random radio pickup I may have fluctuating values of milivolts and therefore I should take an average of these. As for the other two, I do not believe there is much I can do to minimise these with the equipment I have (and with the level of accuracy I have will these matter?). Nevertheless you have given me many topics which sound fascinating and I will look into contact potentials especially. As for results, I cannot hope to get completely theoretical values due to systematic errors such as concentration and resistance. However as they are systematic, although my graph my have a slightly incorrect gradient and y-intercept, I should find a trend similar to that of the nernst equation.
  6. The aim of the experiment is to look into the effect of change of concentration of electrolyte on cell voltage. This is to help me test the nernst equation. The document was written by me and I have no hope of recording to such precise values however I do want at least milivolts. I understand my values will not be completely correct, the point is to test the equation, not get exact values. I have been given an electrometer by the university. With resolution 100 micro volts and going up to 2V I should be able to obtain values from this.
  7. OK so after talking through with a few teachers we believe a potential divider won't work and the reasoning is this: Say we had 1000:1 . Our 1000 ohm would give 1.0044 V and our 1 ohm would read 0.0010044 and therefor we would never be able to read that on my equipment. Potentiometric voltmeters require precise resistors whereas the ones I have available have 10% error. As for circuit theory I have looked into potential dividers and resistors in series and parallel but not much else. My plan for now is to try and talk to the local university and see if they have any equipment I could use or get lab time. If you think of any other possible options, I will be here. Thanks
  8. Thanks for your response, A potential divider is probably my best bet. My multimeter can go down to a 10th of a milivolt. Should I use a resister setup of 1000:1 or of 10000:1? The Nernst equation is not on the A-level specification, it is my own work. Thanks for your help!
  9. Hi, I am a secondary school student from England looking into advanced chemistry. I have been learning about the nernst equation and am planning an experiment on this topic. I need to measure a change of 0.001 volts (a milivolt) with a starting voltage of 1V. How can I do this, my school has a multi-meter however its milivolt reader only has 3 significant figures (up to 99.9 mV). At 1.001 volts I would need up to 9999 mV. Find attached proposed experiment Thanks Nernst equation experiment.docx
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