chemistry question

[echo4747]

Been so long since I've had to do make this I forgot how:

-I would like to prepare a .2Normal EDTA solution how many grams of EDTA is needed to make 500ml?

 

[esquared]

Depends if you are using EDTA free base or a salt. Need to know the MW.

If you're using the free base its 292.24 g/mole

292.24 g/mole x 0.5 Liter x 0.2 moles/liter = 29.22 grams for 500 ml

This is not very soluble in water and the pH will need to be between 10-11 IIRC.
It needs large amounts of 3-5N NaOH for get it in solution.

Easier way to make is to make sure you have EDTA as in a sodium salt.
http://www.sigmaaldrich.com/catalog/product/mm/ex0539?lang=en&region=US
Solubility isn't a problem them as its 100 g/L in water.
372.24 x 0.5 x 0.2 = 37.22 grams for 500 ml

 

[esquared]

Also, make sure that you QS (Quanity sufficient) it properly. Especially if you're using freebase.
Because you will add the EDTA to around 1/2 of the water and stir on a stirplate while adding
NaOH. When its all dissolved you will then bring the final volume up to 500 ml.

 

[echo4747]

Thanks for your help. The EDTA I'm using is: Disodium Salt Dihydrate , Crystal ... Does it need to be dried in an oven first
( before dissolving in
di water to 500ml)?

 

[esquared]

From what I see its not hydroscopic (absobs water). As long as it appears dry, that's fine.
This form of EDTA dihydrate can actually lose its two water molecules that are attached to the EDTA molecule if heated to 110C.
so I would not dry it. That would actually change the molecular weight.
Here's the MSDS
http://www.emdmillipore.com/Web-US-...SDS-Start?PlainSKU=EMD_CHEM-EX0539&Origin=PDP

When mixing, put the 37.22 grams in about 400 ml of DI H20 and mix until dissolved. Then add DI H20 to get the final volume of 500ml.

 

[echo4747]

thanks again

 

[MrSquished]

this is all Greek to me

 

[pete6032]

MDMA?

 

[Zanovar]

MDMA?

hahah.i love you and forever and always.

 

[Thebobo]

I thinks its Lysergic acid diethylamide.

 

[Brainonska511]

Depending on how concentrated you're making the solution, heat alone may not dissolve the EDTA. You might need some stirring and raising of the pH. Whatever form of EDTA we used to use when I was in the lab always required the addition of sodium hydroxide to get it to dissolve.