I'm assuming you have a container of Analytical Grade reagent (NaCl) which has an expiry date printed on the label and you are concerned in some way that the salt will be "out of date" in some way. The expiry date probably refers to the certificate of analysis rather than the state of the material (salt is fairly long lasting in the solid form).

I would be fairly confident that the NaCl has not broken down to it's constituent atoms in any way. There may be some trace contamination of the salt from previous instances of opening the container to use the contents (dirty spatulas, returning some unused material to the container, break down or wearing away of the container walls etc). There might also be some moisture absorption if the lid was not fully tightened, but on the whole, this salt will still be salt.

When we use any chemical, we need to clearly understand the expiry date of this substance. The validity period not only means a change in its chemical or biological structure, but also a change in its physical state. In your case, NaCl will be further used for salt extraction of moringa oleifera seeds. Although its chemical structure is relatively stable, the physical state of NaCl is likely to change during long-term storage and use (such as water absorption, etc.). This series of small deviations may affect your experimental results. I recommend that if you want to accurately achieve your desired goal, you should choose a new chemical instead of an expired one.

Thank you Weihao Meng