Sodium Hydroxide: solution shelf-life?

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.

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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?

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'.

Thanks, Pete. Does that include a bottle that is repeatedly opened

and closed and not filled completely?

Ted:

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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.

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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.

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Yours chemically.

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Richard

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?

Suggestion: review freshman chem.

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Even though sodium ion and hydroxide ion are stable, I wouldn't make

too much solution especially if frequent bottle opening is expected,

concentration is rather low, or stable pH is required.

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There are some CO2 available in air, which is easy to dissolve in

alkaline solutions. The result will be in loss of OH ions

because CO2(g) + water produces protone and this protone and OH-

form water. Thus H+ is removed from one side of CO2 equation and

therefore CO2 is extremely readily soluble into hydroxide solution.

Sodium hydroxide is a strong base, near 100% dissociation

and pH is not buffered at all.