Question

10 Equal masses of the following non-volatile solutes are dissolved in 1000g of H20(0). Which solution will have the LOWEST freezing point. A. NaCl B. KCI C. LiCl D. CsCl E. RbCl Suppose that the reaction A → products proceeds in one step and is exothermic. It has an activation barrier of 75 k/mol. How would the energy diagram change if a catalyst is added to the reaction? Select all the statements that could be true. 11 Addition of the catalyst can decrease the barrier of activation. Addition of the catalyst can cause the reaction to have more than one transition state. Addition of a catalyst can decrease the rate of the reaction X. Y. Z. B. Y C. Z D. X andY E. X, Y, and Z

Answer 1

10)

delta Tf = i*Kf*m

i and Kf is same for all

For lowest freezing point, delta Tf should be maximum. That is molality, m should be maximum.

m = mol of solute /mass of solvent

since mass of solvent is same for all,

m is maximum when mol is maximum

mol = mass/molar mass

since mass is same for all,

mol is maximum when molar mass is minimum

molar mass is minimum for LiCl

So, LiCl will have lowest freezing point

Answer: C

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