Lab Report Solubility Phenol - Practical Study And Calculation Theory PDF

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Introduction: Miscibility refers to the ability of a liquid to dissolve completely in another liquid solution. Two liquids which completely miscible will form a homogeneous solution. Miscibility can be categorized into miscible, partially miscible and immiscible. For instance, if two different layers between two liquids will not form in mixed solution, it is label as miscible but if two different layers does form in a mixed solution, this condition refer to immiscibility. For example, oil and water are immiscible liquid, water and ethyl alcohol are completely miscible and phenol and water are partial miscibility.

In general, critical solution temperature(CST) means the temperature at which miscibility completely reached, as the temperature is higher or in some cases very low. Both liquids become more soluble as the temperature increases until it reached the critical solution temperature(CST). Normally, two liquids that used are partially miscible under an ordinary condition. In phenol water system, the mutual solubility of two conjugate phases increase with temperature until the composition becomes identical. The maximum temperature at which the two phases region is termed the critical solution temperature(CST).

Under the critical solution temperature(CST), the liquids will be immiscible at any temperature by forming two different layers of liquids. Above or at the critical solution temperature(CST), miscible liquids are formed with only one layer. Any two liquids have tendency to form a closed system because the existence of both upper and lower critical solution temperatures(CST). However, the temperatures are very difficult to be determined except for nicotine-water. The composition for two layers of liquids in equilibrium state is constant and it does not depend on the relative amount of these two phases at any temperature below the critical solution temperature(CST).

Solubility can be defined by using Gibb’s phase rule. Gibb’s phase rule can be describes as the possible number for degrees of freedom in a closed system at equilibrium state, in terms of the number of separate phases and the number of chemical substances in the system. It can be expressed as :

F=C–P+2

F is the number degrees of freedom in system. C is the number of components and P is the number of phases present. Objectives: 1. To observe the effect of temperature on the solubility of phenol in water. 2. To determine the critical solution temperature(CST). 3. To differentiate between saturated, unsaturated and supersaturated solution. 4. To determine the solubility curve for phenol in water system. Methodology: Apparatus: Hot water bath, thermometer, measuring cylinder, pipette, tube racks, test tube(big), gloves, goggle, waste container, face mask. Reagents: 80% Phenol, distilled water. Procedure: Result: Concentration 0.8 0.6 0.4 0.2 0.1 0.05 Concentration of Phenol (%) 80 60 40 20 10 5

Temperature 1 65 69 70 71 69 65

Temperature 2 Average Temperature 25 45 59 64 68 70 65 68 61 65 46 55.5

Average Temperature (°C) 45 64 70 68 65 55.5

Solubility Curve for Phenol-Water System 80 70

Temperature (°C)

60 50 40 30 20 10 0 0

10

20

30

40

50

60

70

80

90

Average Temperature (°C) Concentration of Phenol (%)

Discussion: Answers: 1. One important factor governs the solubility of phenol in water is temperature. As temperature increases, the solubility of phenol in water increases because the kinetic energy of molecule is higher. As phenol dissolves in water is an endothermic reaction, so energy is absorbed from the surrounding.

2. Dilution is the process of decreasing the concentration of the solute by adding more solvent to the solution. Adding more solvent without adding any solute make a solution become more dilute. Based on the experiment that we conducted, we had given 0.8M of phenol and needed to dilute the solution into 0.6M, 0.4M, 0.2M, 0.1M, 0.05M by adding certain volume of water. We can determine the volume of water and phenol needed by using formula M1V1 = M2V2. So, as more water is added to the phenol, the concentration of the phenol decreases.

3. Differences between saturated, unsaturated and supersaturated: Saturated

Unsaturated

supersaturated

A solution which

the A solution that contains

solvent cannot be added less

solute

more solute. It shows that saturated

than

the

solution.

A solution with more solute

than

saturated

It solution that contain more

the solution has reached completely dissolved, no

undissolved solute. It has

its equilibrium.

remaining substances left.

tendency

to

form

The solution has not yet

precipitate

or

crystal.

reaches its equilibrium.

When

disturb

its

state

by

we

equilibrium

increasing the temperature (one of the factors), the solute will be dissolved.

4. Solution of phenol in water is preferable in dispensing practice compared to solid phenol because liquid form is easier to be absorbed than solid form. Solution of phenol is readily to be absorb. If phenol is solid, it will take more time to breakdown. So, solution phenol will give faster effect compared to solid phenol. 5. Phase diagram 6. Before the tubes of solution of phenol in water immersed in hot water bath. There is one phase exist. Both solution of phenol and water are in liquid phase. The degree of freedom in that particular time: F= C-P+2 = 2-1+2 =3 When the number of phase is 1, the degrees of freedom is 3.

A few minutes after the tubes is removed from the water bath, the precipitate is formed. There is two phases which are solid and liquid. The degree of freedom in that particular time: F= C-P+2 = 2-2+2 =2 When the number of phases are 2, the degrees of freedom is 2.

To conclude, the greater the number of phases in equilibrium, the fewer the degree of freedom.

Conclusion References : Bofa, T. (n.d.). Miscibility. Retrieved September 23, 2018, from http://science.jrank.org/pages/4382/Miscibility.html Critical Solution Temperature. (n.d.). Retrieved September 23, 2018, from https://www.merriam-webster.com/dictionary/critical solution temperature...