Question

1) We have assumed that the unknown does not dissociate into more than one particle when

dissolved. If this was an incorrect assumption and the solid did dissociate slightly. Then how

would the calculated molar mass of solute from our experiment differ from the actual molar mass?

The calculated would be (too high, too low or unaffected) compared to the actual? Explain briefly.

2)If you measured the experimental freezing point of 30g cyclohexane with 0.012mols of Toluene

(MWT= 92.15) and compared it to a measurement of 30g cyclohexane with 0.012mols

benzophenone (MWT = 182.22). What would you expected to observe about the two separate

freezing points? Explain Briefly

3) Why is cyclohexane used as a solvent in this experiment instead of water? Water is much safer and much cheaper.

Answer 1

solute may associate , dissociate or not change in solution.

in case of dissociation observed molar mass will be lower than calculated.

in case of association observed molar mass will be higher than calculated.

in case of neither association nor dissociation observed value is close to actual value.

2) both solutions toulene and benzophenone shows same freezing point.

because colligative property depends only on number of particles not on mass. both toulene and benzophenone 0.012 moles means same number of particles.

3) because both are soluble in cyclohexane not in water..