This is quite a dumb question to ask...but my googling skills failed me.
When companies like Sigma Ald. sell their stuff, whether its solvents or chemicals, all has purity percentage on them (99%, 99.5% etc)
What are the other 1%,0.5%etc contained in it?
Say, for instance, acetone 99%. What is other 1%? water, methanol, or other stuff arising from its synthesis?
Is it possible that the impurity may affect the reaction? (like say, if u are using organic solvent and cant have water contamination but 1% impurity turns out to be watere etc)
What tests do they use to confirm the purity, and is it possible to know what the impurities are beforehand?
Also, (this is kinda difference from others) stuff like Pt/C 40% : whats the other 60%? If the answer is carbon im just dumb.