Question

What mass of anhydrous salt is required to prepare a `50*g` mass of `"acetic acid trihydrate"`, `H_3C-CO_2H*3H_2O`?

Answer 1

You want approx. `30*g` of the anhydrous salt.

Explanation:

Sodium acetate trihydrate has a formula mass of `136.04*g*mol^-1`.

And thus a `50*g` mass is a molar quantity of..........

`(50*cancelg)/(136.04*cancelg*mol^-1)=0.368*1/(1/(mol))=0.368*mol.`

Now this is `0.368*mol` with respect to sodium and acetate ions, but `1.10*mol` with respect to water.

And so we use the given molar quantity to calculate an equivalent mass of the ANHYDROUS salt:

`0.368*cancel(mol)xx82.03*g*cancel(mol^-1)=30.2*g`