Depression in freezing point of 0.1 molal solution of HF is `-0.201^(@)C`. Calculate percentage degree of dissociation of HF. `(K_(f)=1.86 K kg mol^(-1))`.

Answer

`8.06 %`

Explanation

Observed `DeltaT_(f)=0.201^(@)C`. Calculated `DeltaT_(f)-K_(f)xxm=1.86xx0.1=0.186^(@)C" "therefore" "i=(0.201)/(0.186)=1.0806`
`{:(HF,hArr,H^(+),+,F^(-),),("1 mol",,"0",,"0",),(1-alpha,,alpha,,alpha",", "Total "=1+alpha.." Hence, i"=1+alpha" or "alpha=i-1=0.0806=8.06%):}`