[hildebramdt]

The solubility of sodium carbonate in 100 g water is 25 g at 22 C. How many grams of the hydrtae Na2 CO3. 10H20 can be disolved in 100 g of water at 22 C?

1)  0 556g        2)0 762g        3)9 27g        4)67 5g     5)  81 7g           6) 117g

if you can , explain it, please

[AWK]

You should express mass of anhydrous Na2CO3 and mass of water in hydrate as a function of the mass of hydrate. Then use definition of solubility.
Show your attempt!.

[Vidya]

Find the number of moles in Na2CO3 =mass in gms /molar mass           =25/106=0.2358moles
    Moles of water in 1mole of sodium carbonate =10
   moles of water in 0.2358 moles of sodium carbonate =10X0.2358=2.358
   mass of water in  in 2.358 moles of water= 2.358 X molar mass of H2O
                                                              2.358X 18=42.45gm
 mass of hydrate soluble in 100gm of H2O
                            =25  +42.45                                                       
                       =67.45gm=67.5 gms