Jawapan

2016-07-28T17:09:42+08:00
Barium chloride reacts with sulfuric acid to produce HCl and barium sulphate (BaSO4): 

y............................1.864 
BaCl2 + H2SO4 -> BaSO4 + 2 HCl 
1 mole...................1 mole 
208g......................233g 

y is the mass of "anhydrous" BaCl2 in the 1.936 g of hydrate. 

y = (208*1.864)/233 
y=387.712/233 
y=1.664 g 

One mole of BaCl2 is 208g, so 1.664g will have 1.664/208=0.008 moles BaCl2. Note this... 


The water in the original BaCl2 xH2O is: 1.936g-1.664g=0.272g. In moles, this is 0.272/18=0.0151 moles of water. 

So.... we have 0.008 moles BaCl2 and 0.0151 moles of water together. 

0.0151/0.008=1.88 

You can round it up to 2 (I rounded the the atomic masses to make calculation easier) 
Hope this helps