Solutions

Solutions

Question

Calculate the boiling point of the solution when 4g of MgSO4 (M =120 g mol-1) was dissolved in 100g of water,assuming MgSO4 undergoes complete ionization.

(Kb for water =0.52 K kg mol-1)

Answer
increment straight T subscript straight b space equals space iK subscript straight b straight m
straight i space equals space 2
equals space straight i space straight x space straight K subscript straight b space straight x space fraction numerator straight w subscript 2 space straight x space 1000 over denominator straight M space straight x space straight w subscript 1 end fraction
equals space 2 space straight x space 0.52 straight K space kg space mol to the power of negative 1 end exponent space straight x space fraction numerator 4 straight g space straight x space 1000 space straight g divided by kg over denominator 120 straight g divided by mol space straight x space 100 straight g end fraction
space equals fraction numerator space 2 space straight x space 0.52 over denominator 3 end fraction
boiling space point space of space water space equals space 373.15 divided by 373 straight K
straight T subscript straight b space equals space straight T subscript straight b superscript 0 plus increment straight T subscript straight b
equals 373.15 space straight K space plus 0.346 space straight K divided by 373 straight K plus 0.346

equals space 373.496 straight K divided by 373.346 straight K

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