Question

In: Chemistry

(5) Suppose you have three test tubes with three substances, A, B, and C with nearly...

(5) Suppose you have three test tubes with three substances, A, B, and C with nearly the same melting point. Describe how would you proof experimentally (having only melting point apparatus in hand) that these are not the same substances.

Expert Solution

Add the same amoun of impurity, such as nonvolatyle sample

then

Apply Colligative properties

This is a typical example of colligative properties.

Recall that a solute ( non volatile ) can make a depression/increase in the freezing/boiling point via:

dTf = -Kf*molality * i

where:

Kf = freezing point constant for the SOLVENT;

molality = moles of SOLUTE / kg of SOLVENT

i = vant hoff coefficient, typically the total ion/molecular concentration.

At the end:

Tf mix = Tf solvent - dTf

Then

Each species has different Kf

expect different depression points

calcualte depression points and compare with respect to Kf constant

queen_honey_blossom answered 2 years ago

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