Physical Principles II

CEBU CITY Chemical Engineering Department

Name: Juphil Lamanilao Date: October 15, 2009

Course & Yr: BSChE-4

I.TITLE: Distribution of a Solute between Immiscible Solvents

II.OBJECTIVE:

To determine the distribution coefficient K.

III.APPARATUS:

(3) 100-ml separatory funnels, (3) 100-ml Erlenmeyer flasks, 100ml volumetric flask, 25-ml & 10-ml pipette, 1N CH3COOH, glacial CH3COOH, CCl4, ether, 0.5N NaOH, 0.01N NaOH

IV.SKETCH:

Distribution of a Solute between Immiscible Solvents 1

Physical Principles II

V.TABULATED DATA & RESULTS:

Solution Volume of Sample

Volume of H2O added

Volume of NaOH used

Concentration of HAc (ml)

Distribution

Coefficient

UPPER LOWER UPPER LOWER UPPER LOWER UPPER LOWER K

0.5N HAc + diethyl ether

2 ml 2 ml 75 ml

75 ml

1.3 ml

2.8 ml

0.325

0.70 1.3

1N HAc + diethyl ether

2 ml 2 ml 50 ml

50 ml

2.5 ml

4.2 ml

0.625

1.05 1.8

2N HAc + diethyl ether

2 ml 2 ml 25 ml

25 ml

5.5 ml

12 ml 1.375

3.0 2.2

VI.SAMPLE COMPUTATIONS:

UPPER: LOWER:

a. 2x = 1.3(0.5) = 0.325 a. 2x = 2.8(0.5) = 0.70b. 2x = 2.5(0.5) = 0.625 b. 2x = 4.2(0.5) = 1.05c. 2x = 5.5(0.5) = 1.375 c. 2x = 12(0.5) = 3.0

Distribution of a Solute between Immiscible Solvents 2

Physical Principles II

VII.DATA ANALYSIS:

The addition of an excess of a liquid to a mixture of two immiscible liquids will results in the additive being distributed between two phases. That is, for every mixture of CH3COOH and diethyl ether with corresponding increasing concentrations at the same time the distribution coefficient (K) also increases relatively. In addition, more volume was consumed on the lower portion of the mixture as the dissolved substance between the two given immiscible solvents distribute itself to a definite equilibrium. If the additive is added at less than saturating amounts, it will also become distributed liquids at a defined concentration ratio.

VIII.APPLICATION TO ChE:

The influence of solvent-solvent interactions on the solubility of drugs is a critical topic of which future chemists need to have a thorough grasp. Also applied to chromatography where the stationary phases are water molecules bound to a cellulose matrix. It is a critical parameter for purification using ozone melting.

IX.CONCLUSION:

In the experiment, a solute is distributed between two phases in a dynamic (heterogeneous) equilibrium. If a substance is added to a mixture which is soluble to a greater or lesser extent in both immiscible liquids, on shaking and then allowing the mixture to settle, the concentrations in each layer become constant. However, there is continual interchange of solute between the liquid layers via the interface. If more of the substance is added to the system, the solute will distribute itself between the immiscible liquids so that the ratio of the solute concentrations remains the same at constant temperature independently of the total quantity of a solute in the same molecular state. When the molecular weight of a solute is different in the two solvents, the ratio of the concentrations in the two phases is not constant,

Distribution of a Solute between Immiscible Solvents 3

Physical Principles II

and in contrary, if the ratio varies considerably with concentration, it may be deduced that the molecular weight of the solute is not identical in the two solvents.

Distribution of a Solute between Immiscible Solvents 4