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You can't control both voltage and current electrically: Your power supply will hold one or the other constant, but the properties of the electrolytic cell will then determine the other one. So you need to hold all of the chemical parts of the experiment constant: Have a large ion bath so that the concentration doesn't change much as the plating takes ...


4

I just did the experiment suggested by @porphyin. I used a 405 nm laser diode built into a toy "Space Gun" and the orange long pass filter shown in the figure below: The results are in the next dark figure: The spots on the paper are not fluorescence of the paper (see the violet fluorescence of the paper around the dark shadow of the filter) and are not ...


4

Try to change the geometry of your electrodes. For example, increase or decrease the distance between the electrodes. This will modify the internal resistance of the solution. So if you have a generator producing a constant voltage, you may reach the desired currant, simply by changing the distance between the electrodes. Of course the electrodes must be ...


4

If you mean the test tube containing the solids (reaction tube), then that tube faces downwards to promote the flow of gas into the receiving tube. The idea is to let the gas sink away from the reaction zone and towards the receiving tube as it cools and becomes more dense. The receiving tube, of course, faces down so that the ammonia gas, lighter than air,...


3

Oxalic acid is a relatively strong acid for a carboxylic acid, and according to my sources below, can auto-catalyze the reaction with Potassium Permanganate. So, the reaction you performed was likely just the same mechanism that you have seen everywhere else. My source is as follows: Kovacs K.A.; Grof P.; Burai L.; Riedel M. (2004). "Revising the mechanism ...


2

You could create a constant-current source instead of using an off-the-shelf power supply. There are also off-the-shelf constant-current supplies, so ask your lab manager if that's a resource. An EE colleague can set this up for you if it's too far outside your domain. Here are a few articles as starting points. Total cost should be < $15. http://www....


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You may find information from the US Federal government relating to this questions at the following sites: https://www.epa.gov/hwgenerators/steps-complying-regulations-hazardous-waste https://www.epa.gov/rcra/resource-conservation-and-recovery-act-rcra-regulations Furthermore, your organization (theoretically) has a local waste discharge permit that it must ...


2

Changes in volume The chemical reaction for burning a candle is something like this: $$\ce{C25H52 + 38 O2(g) -> 25 CO2(g) + 26 H2O(g)}$$ For every 38 dioxygen molecules used, you are making 25 carbon dioxide molecules and 26 water molecules (which start out as a gas, but will condense once they reach an area of lower temperature such as the glass ...


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There is a slight deviation in the literature as to what the hybrid composites are. Originally, materials were considered hybrid composites if both inorganic (e.g. clay/silicates as the hydrophilic component) and organic (e.g. organic polymer as the hydrophobic component) constituents were involved in building up the matrix (see e.g. a review [1]). Another ...


1

For one, pure water has a certain refractive index, $n_D = 1.333$ at a temperature of $20\,^\circ{}\mathrm{C}$. For the other, the presence of a solute alters this optical property, which is used, for example to estimate the sugar content in grapes (see, for example an earlier answer by mine here). «Calibrating your tools» would now request that you ...


1

I have found in Germany sugar crystals that are about 5 mm thick. If you are able to get some, you may drop one of these crystals in a beaker with 50 mL water and an stirring bar. If not take a standard sugar cube. Using a watch, measure how long it takes for the crystal to be dissolved. Now start again with another rotating speed. Now break a new crystal in ...


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