Anidrous, monohydrate or cristallyne

[rui_lourosa]

hello

what i´m asking is if anyone could tell me how can i distinguish

sodium sulfite anidrous and cristal or heptahydrate

 

and

 

potassium carbonate anydrous or monohydrate

 

is there a way to test the chemicals, are they visually different,

because i bought some from a company that does not specifies,

before i had a friend that made developers for me but he is gone and

now i have to make them my self, and i don´t know the appearence or

the weight per volume, of these two important chemicals, please help

[pete_andrews]

Anhydrous chemicals usually have a fine, very white powder appearance, and crystalline is, well, crystalline, like rock salt, or coarse table salt. However, it's possible to grind hydrated crystalline chemicals into a fine powder as well, so the appearance is no guarantee.<p>You really need to get back to your supplier, and find out exactly what they've sold you. They ought to know, if only in order to comply with current safety legislation.<p>If they can't tell you, then find another supplier.<p>As a final resort, you'll have to test the chemicals. Here's a crude test: If you heat hydrated chemicals above 100 degrees C, they will lose weight, usually with a visible outgassing of steam. Weigh a few grams of the chemical accurately, then put it in a microwave oven for a few minutes, or a normal electric oven for half-an-hour at about 200C. If there's a noticeable weight loss, or crumbling, after heating, then the chances are that the chemical was hydrated.<br>NB: The above test isn't infallible, and shouldn't be used on organic compounds.