ted_kaufman Posted July 27, 2001 Share Posted July 27, 2001 Does anyone know what the expected shelf-life of should be? I'm talking about a solution in the 10% range. Also, any idea on how long is might last when filled vs. repeatedly open and partially filled, as would be the case with a solution used for daily use. I'm assuming, of course, a tightly capped amber bottle. <p> Any ideas on extending the working life of the solution--an additive that might prevent it from combining with carbon dioxide when exposed to air, but would not alter its characteristics? Link to comment Share on other sites More sharing options...
pete_andrews Posted July 27, 2001 Share Posted July 27, 2001 A 10% solution of Sodium Hydroxide will keep indefinitely. I'm not being funny; indefinitely is the scientific term for 'until the cows come home'. Link to comment Share on other sites More sharing options...
ted_kaufman Posted July 27, 2001 Author Share Posted July 27, 2001 Thanks, Pete. Does that include a bottle that is repeatedly opened and closed and not filled completely? Link to comment Share on other sites More sharing options...
richard_ilomaki Posted July 27, 2001 Share Posted July 27, 2001 Ted: <p> Indefinitely - as many times as you open and shut the bottles. The only difference will be a miniscule difference in concentration if the humidity is different each time you open it-the difference being in parts per million. <p> If you took a bottle of 10% NaOH (Sodium Hydroxide) and placed it beside a standard silver print, the print would fade (100 yrs) before the NaOH would change. It may dissolve a bit of the glass bottle, but it would not deteriorate. Of all the photochemicals used, it is most likley the least affected by time or oxygen. <p> Yours chemically. <p> Richard Link to comment Share on other sites More sharing options...
wilhelm Posted July 27, 2001 Share Posted July 27, 2001 Ted, do you, by any chance, have a freezer full of Ektaflex materials, just waiting silently to be awakened by a kiss of Sodium Hydroxide? Link to comment Share on other sites More sharing options...
ryuji_suzuki Posted July 28, 2001 Share Posted July 28, 2001 Suggestion: review freshman chem. <p> Even though sodium ion and hydroxide ion are stable, I wouldn't maketoo much solution especially if frequent bottle opening is expected,concentration is rather low, or stable pH is required. <p> There are some CO2 available in air, which is easy to dissolve inalkaline solutions. The result will be in loss of OH ionsbecause CO2(g) + water produces protone and this protone and OH-form water. Thus H+ is removed from one side of CO2 equation andtherefore CO2 is extremely readily soluble into hydroxide solution.Sodium hydroxide is a strong base, near 100% dissociationand pH is not buffered at all. Link to comment Share on other sites More sharing options...
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