Question

I am finishing up a lab on the Standardization of EDTA and NaOH solutions and I have two questions I am struggling with. The first is why is the EDTA salt dried only at 80C and not at 100 degrees C? The second one is Why is it not necessary to dry the plastic storage bottle before transferring the EDTA into it?

Answer 1

Solution :-

The EDTA salt can absorb the mositure therefore it is important to dry it at about 80 degree C to remove the moisture from it. but still it contains about 0.3% by mass moisture which we need to consider why calculating the concnetraton of the solution.

If it is heated over 100 degree C then the higher temperature may causes the decomposition of the EDTA salt which will result in the incorrect solution.

Drying of a plastic storage bottle is important because if it is not dried well then the bottle may contain the moisture which will again contaminate the EDTA salt and may increase the mass of the EDTA salt. Therefore the keep the EDTA salt pure we need to dry the storage bottle.