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CBSE Class 12-science Answered

Does the molal depression constant for an solvent changes with temperature? For example Kf for water at some temperature is 1.86 then will the value change if it is calculated at some other temperature 
Asked by govtsecschoolnayaganv051 | 21 Apr, 2019, 06:16: PM
answered-by-expert Expert Answer
F r e e z i n g space p o i n t space o f space t h e space s o l v e n t space i n space a space s o l u t i o n space c h a n g e s space a s space t h e space c o n c e n t r a t i o n space o f space t h e space s o l u t e space i n space t h e space s o l u t i o n space c h a n g e s left parenthesis b u t space i t space d o e s space n o t space d e p e n d space o n space t h e space i d e n t i t y space o f space e i t h e r space t h e space s o l v e n t space o r space t h e space s o l u t e left parenthesis s right parenthesis space p a r t i c l e s left parenthesis k i n d comma space s i z e space o r space c h a r g e right parenthesis space i n space t h e space s o l u t i o n. T h e space d e p r e s s i o n space i n space f r e e z i n g space p o i n t space left parenthesis increment T right parenthesis space i s space g i v e n space b y space t h e space e x p r e s s i o n space minus space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space increment T space equals space fraction numerator X subscript s R T squared subscript m over denominator increment H subscript F u s end subscript end fraction space K subscript f space f o r space w a t e r space i s space a n d space c a l c u l a t e d space t o space b e space 1.8597 space K space k g space m o l to the power of negative 1 end exponent space u sin g space R space equals space 8.314472 space J space m o l to the power of negative 1 end exponent space space K to the power of negative 1 end exponent comma space T m space equals space 273.15 space K comma space a n d space capital delta H subscript f u s end subscript equals space 6009.5 space J space m o l to the power of negative 1 end exponent. space K f space f a l l s space t o space 1.849 comma space 1.830 comma space 1.826 comma space a n d space 1.736 space a t minus 10 space degree C comma space minus 20 space degree C comma space minus 30 space degree C space a n d space minus 70 space degree C comma space r e s p e c t i v e l y a n d space t h e space v a l u e space o f space K subscript f space end subscript space i s space g i v e n space b y space e x p r e s s i o n minus space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space K subscript f space equals fraction numerator M subscript w R T squared subscript m over denominator increment H subscript f u s end subscript end fraction
Answered by Sumit Chakrapani | 22 Apr, 2019, 01:11: AM

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