[MrHappy0]

In a lab we were given an pre-prepared solution of EDTA. The EDTA (pure dihydrate) was dried first at 80 degrees Celsius. How is this done instead 100 degrees Celsius?

I was thinking this is because it decomposes at this temperature but this is not true according to Wikipedia. I see that 100 degrees celsius is approaching it's melting point but I don't see how this would explain anything.


Also, how come you cannot store EDTA in a glass bottle?


Any help out there? If not, can someone help refine my online research efforts. Thanks.

[opsomath]

Also, how come you cannot store EDTA in a glass bottle?

You can. That is the way it is stored in my lab.

[MrHappy0]

Okay, say you are performing the standardization of EDTA. Say it is an unknown concentration and you are using CaCO₃ as your primary standard. We were told not to store our EDTA in a standard glass bottle because it will affect our results. Sooo... why would it do that?

[Borek]

I can only guess the idea is that EDTA can leach Ca from the glass. But I have never heard it mentioned as a problem, and I was taught EDTA solutions stored in glass bottles are stable.

In a lab we were given an pre-prepared solution of EDTA. The EDTA (pure dihydrate) was dried first at 80 degrees Celsius. How is this done instead 100 degrees Celsius?

No idea where the problem is. If procedure calls for using 80 deg C, just use 80 deg C. Why do you think you need 100 deg C?

[MrHappy0]

I am practically rewriting exactly how these questions are stated on my Lab Manual for my Chem 121 Lab. I am sorry if they sound like odd questions but I need to answer them.

Borek, I didn't think of using 100C my professor asked "why wouldn't you want to use it?"  So that is where the problem is.

[Borek]

Googling for EDTA thermal decomposition finds this page:

http://pubs.acs.org/doi/abs/10.1021/ac60163a604

[MrHappy0]

What is the difference between using anhydrous EDTA in this procedure instead of EDTA dihydrate?