Reagent bottle types

Hey, we need a chemistry section on this forum. IMO that is.

@Gonzalo

What do you recommend for reagents of various sorts, particularly acids and bases (around 1N hydroxide or h+, for ex, like HCl)

The ground glass stoppered type look cool but are more expensive than, say, screw top reagent lids. Is there are reason to go with ground glass? I guess it offers exposure to just one material, glass, which is fairly non-reactive.

The down side to ground glass is that it would be a hard vessel to transport or store, not being ‘tip-proof’. And it’s also more expensive.

One more question. I have memory of my college lab assistant telling me that strong hydroxides can react with glass but I generally see that glass is used for NaOH. But I also see recommendations to use HDPE plastic for NaOH, perhaps 1.0 or 0.1N, I’m interested in.

And how about burettes? Can NaOH safely be titrated in a glass burette? I guess it’s a matter of exposure time to the glass and the concentration in use. May not be good to store NaOH in the burette for future titration. Eh?

Cheers,

DJ

I am surprised that anyone would use glass to store sodium hydroxide solutions; concentrated solutions will definitely etch glass over time and you will see that our 10M reagent grade stocks (for serious chemistry) and our 36% tech grade stock solutions (for soapmaking) are stored in HDPE or polypropylene bottles. I suppose dilute solutions like 1M or less would probably be ok, but I would not personally feel comfortable with it for storage. Glass burets are used all the time for titrations with 1M NaOH, but then you dont ever leave the solution in the burette for long periods, you do the titration then clean thoroughly. As you quite wisely note, it is “a question of exposure time”.

Glass, especially ground glass stopper bottles, are traditional for acids. Its just historical, from before we had good plastics. I personally dont like them, too easily broken. If you use screwtop glass bottles, look out for the cap, some cheaper caps get eaten by reagents. I prefer teflon drop bottles for adjusting pH with concentrated acids. Similarly, if you can get teflon stopcocks on glassware instead of the traditional ground glass, it is much better tho slightly more expensive.

Hope this helps.

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Thanks, Gonzalo. looks like PTFE (Teflon) is the safest way to go in all aspects. And I can see the convenience to using a dropper bottle if you don’t care about measuring the titration volume or titrating at a controlled rate as with a burette.

Thanks!!