After adding non-volatile solute freezing point of water decreases to -`0.186^@C`. Calculate `DeltaT_b` if `K_f = 1.86 K kg mol^(-1)`and `K_b = 0.521 K kg mol^(-1)`

Options

A. 0.0186
B. 1.86
C. 0.0521
D. 0.521

Answer

C

Explanation

`DeltaT_f = T_f^@ - T_f =0 -(-0.186^@) = 0.186^@C`
`DeltaT_f = K_f xxm`
`rArr m = (DeltaT_f)/(K_f) = 0.186/1.86 = 0.1 m`
`:. DeltaT_b = K_b xx m =0.521 xx 0.1 = 0.0521 K`