How would you calculate the number of grams and mols of anhydrous salt per 100g hydrate?
A hydrate means that the compound has water molecules attached. Sometimes it has one molecule of water (monohydrate), sometimes two (dihydrate), or even something like 7 molecules of water are attached (heptahydrate). So, without knowing how many water molecules are attaced, we can’t answer your question exactly. But if there is one molecule attached, then you have to add the molar mass of water (18) to that of the anhydrous salt (208.22) and you end up with 226.22 gm/mole for the monohydrate. From this you can see that 208.22/226.22 x100 = 92 percent of this hydrated form is actually the anhydrous salt. So, if you had 100 grms of the hydrate, you really have only 92 percent of the salt, or 92 grams. So, the answer to the first part is 92 grams (assuming you have the monohydrate). The answer to the second part, how many moles of anhydrous salt do you have, is calculated by taking the 92 gms/208.22 = 0.44 moles. We can’t answer the question about the formula of the hydrate except to ass