1.

1.20 gm sample of NaCO_(3) " and " K_(2)CO_(3) was dissolved in water to form 100 ml of a Solution : 20 ml of this solution required 40 ml of 0.1 N HCl for complete neutralization . Calculate the weight of Na_(2)CO_(3) in the mixture. If another 20 ml of this solution is treated with excess of BaCl_(2) what will be the weight of the precipitate ?

Answer»

Solution :Let, weight of `Na_(2)CO_(3) = xgm`
Weight of `K_(2)CO_(3) = y ` gm
` :. X + y = 1.20` gm
For neutralization reaction of 100 ml
Meq. of `Na_(2)CO_(3) + " Meq. of" K _(2)CO_(3) = ` Meq. Of HCl
`RARRX/(106) xx 2 xx 1000+ y/(138) xx 2 xx 1000 = (40 xx 0.1 xx 100)/20 `
` :. 69x + 53Y = 73 .14`
From Eqs. (1) and (2) , we get
`x = 0.5962 ` gm
` y = 0.604` gm
Solution of `Na_(2)CO_(3) " and " K_(2)CO_(3) ` gives ppt. of `BaCO_(3)` with `BaCl_(2)`(Meq. of `Na_(2)CO_(3) + ` Meq. of `K_(2)CO_(3))` in 20 ml = Meq. of `BaCO_(3)`
`rArr ` Meq. of HCl for 20 ml mixture= Meq. of `BaCO_(3)`
`rArr` Meq. of `BaCO_(3) = 40 xx 0.1 = 4`
` (197)/2= W_(BaCO_(3))/E_(BaCO_(3)) xx 1000 = 40 xx 0.1 = 4`
`W_(BaCO_(3))/(197) xx 2 xx 1000= 4`
` :. W_(BaCO_(3)) = 0.394` gm


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