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Calculate the normal boiling point of a sample of sea water found to contain`3.5%` of `NaCl` and `0.13 %`of `MgCl_(2)` by mass. The normal boiling of point of water is `100^(@)C` and `K_(b)("water")= 0.51K kg mol^(-1)` . Assume that both the salts are completely ionised.A. `100.655^(@)C`B. `99.655^(@)C`C. `101.655^(@)C`D. `102.655^(@)C` |
Answer» Correct Answer - A Mass of `NaCl=3.5g`No. of moles of NACl=`(3.5)/(58.5)` Numbers of ions furnished by one molecules of `NaCl` is `2` So, the actual numbers of moles of particals functuion by sodium chloride =`2xx(3.5)/(58.5)` Similarly , actual number of mole sof particles furnished by magnesium chloride `=3xx(0.13)/(95)` total number of moles of particles=`(2xx(3.5)/(58.5)+3xx(0.13)/(95))` `=0.1238` Mass of water =`(100-3.5-0.13)=96.37g=(96.3)/(1000)kg` Molarity =`(0.1238)/(96.37)xx1000=1.2846` `DeltaT_(b)` = Molarity `xxK_(b)=1.2846xx0.51=0.655K` |
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