1.

A mixturecontains NaCland an unknownchloride MCI. (i) 1 g of thisis dissolved in water . Excess ofacidified AgNO_(3) solution is added to it 2.567 g ofwhite precipitateis formed (ii) 1- 0 gof theoriginal mixtureis heated of 300^(@) C. Some vapours comeout whichare absorbed in acidified AgNO_(3) solution . 1.314 g of a whiteprecipitate is obtained.Findthe molecular weightof the unknownchloride.

Answer»

Solution :Supposethe molecular weight of MCI is M .
Given that :
`{:(NaCl = MCI overset(AgNO_(3))to AgCl),("(1 - x) g x g (say)2 . 567 g "):}`
Applying POAC for CL atoms,
moles of Clin NaCl + moles of Cl in MCI = moles of Cl in AgCl
` 1 xx ` moles of NaCl `+ 1 xx ` molesof MCl= `1 xx ` molesof AgCl
`(1 - x)/( 58 . 5) + (x)/( M) = (2 . 567)/( 143 . 5 )`. . . (i)
Now , futher of `300^(@) C ` MCIis supposed to undergo sublimation whileNaCldoesnot.
We have,
`{:(MCI underset(300^(@)C)overset(AgNO_(3))to AgCl),("x g1.341 g "):}`
ApplyingPOAC for Cl atoms,
moles of Cl in MCI= moles of Cl in AgCl
`1 xx ` moles of MCI `= 1 xx ` molesof AgCl
`(x)/( M) = (1 . 341)/( 143 . 5) "". . . (ii)`
From equation (i) and (ii) , we get
M = 53.5
`:.`mol. wt. of MCI= 53.5


Discussion

No Comment Found