5 g of Na 2 SO 4 was dissolved in x g of H 2 O . The depression in freezing point was found to be 3.7 2 ∘ C . If Na 2 SO 4 is 80% ionised, the value of x is approximately. (K f for water = 1

Question

5 g of Na 2 ​ SO 4 ​ was dissolved in x g of H 2 ​ O . The depression in freezing point was found to be 3.7 2 ∘ C . If Na 2 ​ SO 4 ​ is 80% ionised, the value of x is approximately. (K f for water = 1.86°C kg mol -1 ) (Molar mass of S = 32 g mol -1 and that of Na = 23 g mol -1 )

TestHub · Accepted Answer

According to depression in freezing point;

$Δ T_{f} = T_{f} - T_{f}^{'} T_{f}$

$T_{f} = f reez in g p o in t o f p u reso l v e n t$

$T_{f}^{^{'}} = f reez in g p o in t o f so l u t i o n$

$k_{f} = C ryosco p i cco n s t an t or m o l a l d e p ress i o n co n s t an t$

m = molality of solution

i = Van't Hoff factor

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