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I have a range of sodium hydroxide solutions with different concentrations. (from 1.0 mol dm^-3 to 0.5 mol dm^-3). The max volume of each is 100ml. How can you easily dispose of these? Can I pour them down the sink?

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    $\begingroup$ NaOH is the main component of drain cleaners, so… $\endgroup$ – andselisk Nov 14 '19 at 11:54
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    $\begingroup$ It should not be an issue, just use plenty of water. $\endgroup$ – Ezze Nov 14 '19 at 13:16
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    $\begingroup$ Range for sinkable Acids/Bases is between 5.5 and 12 (has to do with the piping, so that may vary a bit depending on the city). So if you're in that range, you're fine to drain it. $\endgroup$ – Michael Green Nov 14 '19 at 16:37
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    $\begingroup$ Depends where you are and what waste water permits you have. At my company, pouring any chemical solutions down the drain is forbidden. $\endgroup$ – Jon Custer Nov 14 '19 at 19:35
  • $\begingroup$ We cannot guess what your local drainage laws or company/university regulations are. Thus, we cannot answer. You better ask whoever is responsible for lab safety/waste disposal. In Munich, pouring acids and bases down the sink was generally fine if large amounts of water were poured after because of a neutralising device in the cellar. But your mileage may vary. $\endgroup$ – Jan Nov 15 '19 at 8:01
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You may pour them down the sink. NaOH will be soon neutralized and destroyed by the CO2 from the atmosphere, or by the bicarbonate ions present in all drinkable calcareous waters.

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    $\begingroup$ Or, add a little NaHCO3 to the NaOH solutions. That gets the process of neutralization started earlier. It takes the edge off, and you can't add too much! $\endgroup$ – James Gaidis Nov 15 '19 at 14:25
  • $\begingroup$ Thanks for help $\endgroup$ – Camden S Nov 17 '19 at 11:05

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