Which one of the following solutes, when completely dissolved in 1kg of water, w

Question

Which one of the following solutes, when completely dissolved in 1kg of water, will cause the greatest elevation in the boilingpoint? If you think that two solutes will have the same effect,enter 0 (the number zero) as your answer.
     A) 1.5 moles of sodium chloride
     B) 1.9 moles of calcium acetate
     C) 1.9 moles of glycerol (anonelectrolyte)
     D) 0.2 moles of sugar (anonelectrolyte)
     E) 0.5 moles of calcium phosphate
Enter A, B, C,D, or E as your answer.
Use the van't Hoff equation. The concentration units aremolality Use the van't Hoff equation. The concentration units aremolality

Explanation / Answer

We know that elevation in boiling point , Tb = i* Kb *m Where i = Vanthoff's factor           Kb = elevation in boiling point constant            m= molality of the solution So Tb      i * m A) 1.5 moles of sodium chloride , NaCl ----- i =2 molality . m = no . of moles / Mass of solventin Kg                  = 1.5moles / 1 Kg                  = 1.5 m       Tb   =  2*1.5 Kb          Tb = 3 Kb B) 1.9 moles of calcium acetate, ( CH3COO)2Ca --- i = 3        m = 1.9 mol / 1 Kg         m = 1.9m Tb   =  2*1.9 Kb   Tb = 3.8Kb
C) 1.9 moles of glycerol (anonelectrolyte)    ---i = 1   Since it isan electrolyte       m = 1.9 mole / 1 Kg Tb   =  1* 1.9 Kb    Tb = 1.9 Kb
D) 0.2 moles of sugar (a nonelectrolyte) --- i = 1     m = 0.2 mol / 1 Kg        = 0.2 m Tb = 1* 0.2 * Kb Tb = 0.2Kb
E) 0.5 moles of calcium phosphate,Ca3(PO4)2   ---- i =5    m = 0.5 mol / 1 kG        = 0.5 m Tb = 5*0.5 Kb     Tb = 2.5 Kb
Since Tb for calcium acetate is more so it have highestelevation in the boiling point. So the corerect answer is B

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