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Common ExperimentsThe purpose of this article is to describe common scientific 'experiments' and the results thereof. Baking Soda/Vinegar A classic, involves pouring/dumping/mixing Vinegar and Baking soda. Water is also a common ingredient. (Apparently, this is also a very good cleaning agent.) Results The mixture foams up as a result of the carbon dioxide that is produced. This effect is often used to make a model of an erupting volcano. Chemical Explanation Acetic Acid (C2H4O2, from the vinegar) reacts with sodium bicarbonate (NaHCO3), forming carbonic acid (H2CO3). This deteriorates into H2O, Na and CO2 (or water, sodium and carbon dioxide). Hydrogen Generator Pieces of metal, i.e. steel wool or magnesium ribbon, are placed in a diluted strong acid; the resulting hydrogen can be captured in one of the following ways, based on the equipment available: - An inverted siphon leading to a bath of soapy water
- An inverted, graduated cylinder to measure volume
- An inverted vessel with a tap. If the metal is held at a fixed height, and the tap is closed, hydrogen will force the acid down out of the vessel, stopping the reaction until the tap is opened.
Results Soap bubbles will float in air and (if small) can be lit on fire. Based on the height of water in a graduated cylinder, the pressure can be calculated. This and the measured volume can be used with the ideal gas law to find the number of moles of hydrogen, and this can be compared to the original mass of the metal to find its formula weight. The self-regulating tap is a good example of negative feedback, and the hydrogen can be put to other uses. Chemical Explanation Metal ions displace hydrogen from the acid. Using magnesium and hydrochloric acid as an example, the reaction is Mg + 2HCl = MgCl2 + H2.
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