Question

On heating 1.763g of hydrated $BaC{l}_2$ to dryness 1.505g of an hydrous salt remained. What is the formula of hydrate ?

• A. $BaC{l}_2$$.H_{2}O$
• B. $BaC{l}_2$$.3H_{2}O$
• C. $BaC{l}_2$$.5H_{2}O$
• D. $BaC{l}_2$$.2H_{2}O$

Answer 1

The correct option is D $BaC{l}_2$$.2H_{2}O$

mass of hydrous salt remain $=1.505g$

moles $=\frac{1.505}{208.23}=0.007227$

Decrease in mass $=$ mass of water

$=1.763-1.505=0.258g$

In this case mole should be equal

so, $\frac{0.258}{x\times 18}=0.007227$

$x=2$ (means dihydrate)

hence Ans - $BaC{l}_2.2H_{2}O$

Ans- D