Question

guys please help me with this ....
A white crystaline solid X is treated with con sulphuric acid .A colorless gas Y is evolved even when the reaction mixture is not heated and lot of frothing takes place in the reaction mixture .the gas Y fumes strongly in air and gives dense white fumes with ammonium hydroxide solution.identify the gas Y ....IF the solid contains sodium as cation , identify X

Answer 1

Hey Friend,

Answers -

X ---> NaCl
Y ---> HCl (g)

Explanation -

White crystalline salt containing Na+ can be any sodium salt. But, the gas evolved fumes strongly in air and gives dense white fumes with NH4OH is HCl.

HCl + NH4OH ---> NH4Cl + H2O

Hence, the sodium salt must contain Cl - .ions.

Therefore, the white crystalline salt or X is NaCl.

The second reactant is known to us, H2SO4
Therfore, 

2NaCl + H2SO4 ---> Na2SO4 + 2HCl 

Hence, the gas formed is HCl or hydrogen chloride! 

Observation -

No heat is supplied to the reactants.
Frothing takes place due to the presence of HCl.

Hope it helps!