Question

Arrange the following in the increasing order of :
(i) Freezing Point
(ii) Boiling point
CaCl2(0.1M), NaCl(0.1M), AlCl3(0.1M), C6H12O6(0.1M)​

Answer 1

Answer:

(i) Freezing point : AlCl₃ < CaCl₂ < NaCl < C₆H₁₂O₆

(ii) Boiling point : C₆H₁₂O₆ < NaCl < CaCl₂ < AlCl₃

Explanation:

We know that,

From the colligative properties,

• Change in Freezing point => $\Delta f = T_f\, ^\circ - T_f = i \times k_f \times m$

Tf° = Freezing temperature

Tf = Freezing temperature after adding the solute

i = Vant hoff factor  ∝ number of atoms present in a compound

kf = Cryogenic constant

m = molality

So, as we are subtracting the freezing temperature after adding solute, it means temperature is reduced after adding the solute

As Molarity is same for the given question, it depends upon the i which is directly proportional to number of atoms present in a compound.

Hence, Freezing point order will be indirectly proportional to number of atoms present in a compound.

[Atoms are : CaCl2 = 3; NaCl = 2; AlCl3 = 4; C6H12O6 = 1 (Glucose doesnt dissociate as it is covalent)]

∴ Order is : AlCl₃ < CaCl₂ < NaCl < C₆H₁₂O₆

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• Change in Boiling point => $\Delta b = T_b - T_b\, ^\circ = i \times k_b \times m$

Tb° = boiling temperature

Tb = boiling temperature after adding the solute

i = Vant hoff factor  ∝ number of atoms present in a compound

kb = Ebullioscopic constant

m = molality

So, as we are subtracting the boiling temperature , it means temperature is increased after adding the solute

As Molarity is same for the given question, it depends upon the i which is directly proportional to number of atoms present in a compound.

Hence, boiling point order will be directly proportional to number of atoms present in a compound.

[Atoms are : CaCl2 = 3; NaCl = 2; AlCl3 = 4; C6H12O6 = 1 (Glucose doesnt dissociate as it is covalent)]

∴ Order is : C₆H₁₂O₆ < NaCl < CaCl₂ < AlCl₃

Hope it helps!