Aqueous solutions of NaOH are typically stored in plastic bottles because these solution slowly dissolve glass to form solutions of sodium silicate. why, then, can a glass buret be used to deliver an aqueous solution of NaOH for accurate titration of an acid as in this experiment?

Such reaction's kinetics is slow.

Explanation:

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In this case, in quantitative analysis when using sodium it is mandatory to use a glass buret for titrations as it is accurate in terms of measuring volume; however, when sodium hydroxide is in contact with the glass, a very slow rate is present when it reacts with the silicates in the glass, forming sodium silicate, such rate is in the order of 1.3×10⁻⁴ and 4.3 × 10⁻⁴ g/(m² s). In this manner, as an experiment does not take more than 10 minutes (typical titrations) the time is not enough to for a considerable amount of sodium silicate, that is why its use is widely enforced.

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