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Name: JOANNA CELESTE Meters. QUINTANA Day performed: NOVEMBER. 12, 2012 Section: C-1L Date posted: NOV.

21 years old, 2012 Group Number: several Exercise Number 2 COLLIGATIVE PROPERTIES (Full Report) My spouse and i. INTRODUCTION Colligative properties In liquid alternatives, particles happen to be close together and the solute elements or ions disrupt intermolecular forces between the solvent molecules, causing changes in those homes of the solvent that hinge in intermolecular attraction. For instance , the freezing point of the solution is leaner than regarding the from the pure solvent and the boiling point is definitely higher.

Colligative properties of solution happen to be those that be based upon the concentration of solute particles in the solution, regardless of what kinds of contaminants are present the greater the attention of virtually any solute, the bottom the freezing point plus the higher the boiling stage of a answer. FREEZING POINT LOWERING A liquid starts to freeze when ever temperature is definitely lowered towards the substance’s freezing point as well as the first few molecules cluster with each other into a ravenscroft lattice to form a tiny volume of solid.

As long as both solid and liquefied phases are present at the cold point, the pace of crystallization equals the interest rate of burning and there is a dynamic sense of balance. When a solution freezes, a couple of molecules of solvent bunch together to form pure sturdy solvent and a energetic equilibrium is placed between the solution and the stable solvent. Regarding a solution, the molecules inside the liquid in contact with the sturdy solvent are certainly not all solvent molecule.

The rate at which substances move from solution to stable is for that reason smaller that in the pure liquid to attain dynamic equilibrium there must be a corresponding smaller rate of escape of molecules from solid crystal lattice. This kind of slower charge occurs by a lower temperatures and so the abnormally cold point from the solution is leaner than regarding liquid solvent. The difference in freezing stage? Tf can be proportional towards the concentration in the solute just as as the boiling point elevation.? Tf = Kf? msolute? solute

Here likewise, the proportionality constant Kf depends on the solvent and not the sort of solute and isolute symbolizes the number of debris per method unti of solute. Intended for water, the freezing stage constant is -1. 86 oC-kg/mole. Very cold point or melting stage is the temp of change between sound and water. Melting point can be scored more accurately than freezing factors. This is becauses so in freezing point measurements, supercooling may happen which will yield a reduced than sslkdjs freezing (melting point).

CHANGES IN VAPOUR PRESSURE: RAOULT’S REGULATION At the surface of an aqueous solution, you will discover molecules of water and ions or molecules from your solute. Drinking water molecules can leave the liquid and enter the gas phase, exerting a fumes pressure. However , there are not as many normal water molecules at the surface as with pure drinking water, because some of them have been out of place by mixed ions or perhaps molecules/ consequently , not as many water substances are available to leave the liquid area, and the fumes pressure is lower than those of pure drinking water at the temperature.

From this analysis, it may make sensory faculties that the vapour pressure with the solovent above the solution, Psolvent, solution, that is certainly, to their mole fraction. Hence, since Psolvent? Xsolvent, we can write Psolvent = Xsolvent? K (where K can be described as constant). This kind of equation informs you that, in the event that there are just half several solvent molecules present in the surface of the solution because at the area of the real liquid, then a vapour pressure of the solvent above the remedy will only end up being half since great since that of the pure solvent at the same temperature. If we are dealing just with real solvent, the above equation turns into Posolvent sama dengan Xsolvent?

T where Posolvent is the fumes pressure with the pure solvent and Xsolvent is corresponding to 1 . This means that Posolvent sama dengan K, that is certainly, the constant T is just the vapour pressure from the pure sovent. Substituting pertaining to K in the foremost equation, we arrive at an formula called Raoult’s law: Psolvent = Xsolvent? Posolvent In case the solution includes more than one unstable component, after that Raoult’s law can be crafted for any the type of component, A, as PA = XA? PoA Such as this ideal gas law, Raoult’s law is actually a description of any simplified model of a solution.

An excellent solution is one that abide by Raoult’s law/ although many solution aren’t ideal, in the same way most gases are not great, we work with Raoult’s regulation as good approximation to answer behaviour. In just about any solution, the mole fraction of the solvent will be less than you, so the fumes pressure in the solvent more than an ideal answer (Psolvent) has to be less than the vapour pressure of the real solvent (Posolvent). This fumes pressure lowering,? Psolvent, is given by? Psolvent = Psolvent? Posolventwhere Psolvent &lt, Posolvent Boiling point elevation

Raoult’s law tells us that the fumes pressure of the solvent more than a solution has to be lower than that of the real solvent. Presume for example you have a solution of your non-volatile solute in the volatile solvent benzene?? II. MATERIALS A. Reagents 4. 00 g naphthalene 0. twenty g not known solute A unknown solute B (assigned amount every group) unadulterated water W. Apparatus 250-mL beaker 400-mL beaker 100-mL graduated tube test pipes thermometer straightener stand, iron ring, flat iron clamp sizzling plate C. Other Apparatus wire gauze tissue conventional paper graphing newspaper timer 3. PROCEDURE Freezing Point of Naphthalene

In a clean and dry test pipe, 2 . 0 g of naphthalene was weighed. To measure the temp while warming, a thermometer was hanging by cells paper on the mouth of the test pipe. It was put into a water bath while using water level over a sample inside the test conduit. To avoid the contact of the test conduit to the underlying part of the bathtub, it was maintained an flat iron clamp. The water bath was then heated until the complete sample offers melted and until the heat of the test reached 90o C. The flame was put off as well as the temperature browsing was recorded just about every 15 seconds until the temperature offers fallen to 70oC.

The set up was put aside for part of the experiment. Data accumulated were tabulated and drawn for analysis and analysis. Freezing Level Depression of Naphthalene Pre weighed 0. 20 g of unfamiliar solute A was added to the previous build of naphthalene. The same treatment was done with it. The thermometer was again suspended at the mouth area of the evaluation tube simply by tissue paper. With the help of straightener clamp, it absolutely was again put in a drinking water bath, with all the water level over a sample in the test pipe, to avoid get in touch with to the bottom level of the bath.

The water bathtub was then simply heated until the entire sample of not known solute A and naphthalene has melted. When the temperature reached 90oC, the fire was defer. The temp reading was written every no time until the temp has gone down to 70oC. Data was also tabulated and drawn together with the data from freezing point of naphthalene. Boiling Point of Water In a 250-mL beaker, 100-mL of unadulterated water was boiled until it completely boiled. The temperatures reading was recorded. In a separate 250-mL beaker, 0. twenty g of unknown solute B was dissolved in 100-mL unadulterated water.

This is also warmed until it finally boiled. The boiling level was likewise recorded. It had been tabulated along with the boiling parts of solutions with varying levels of solute from all other groups. Comparison was made to get evaluation from the results. 4. DATA/OBSERVATIONS Desk 1 . 1 ) Observations upon cooling of naphthalene at 15-second periods. Time (sec. )Temperature (oC)Appearance 1590clear liquefied 3090clear water 4587clear liquid 6086clear the liquid 7585clear water 9085clear liquid 10584clear liquid 12084clear water 13583clear water 15083clear the liquid 16582clear liquefied 18081clear liquefied 9581clear liquid 21080clear water 22580clear liquid 24079clear water 25579clear water 27078clear water 28577clear the liquid 30077clear water 31576solidification 33075solidification 34575 36075 37575 39075 40575 42075 43575 45075 46575 48075 49575 51075 52575 54075 55575 57075 58575 60075 61575 63075 64574 66074 67574 69074 70574 72073 73573 75073 76572 78072 79571 81070 Mass of naphthalene employed (g): 2 . 00 g Table 1 . 2 . Findings on chilling of answer of naphthalene and unfamiliar solute in 15-second span. Time (sec. )Temperature (oC)Appearance 1590clear water 3090clear liquefied 587clear liquefied 6086clear liquid 7585clear the liquid 9085clear water 10584clear the liquid 12084clear liquid 13583clear the liquid 15083clear the liquid 16582clear water 18081clear water 19581clear liquefied 21080clear water 22580clear liquid 24079clear liquid 25579clear the liquid 27078clear liquid 28577clear liquid 30077clear the liquid 31576clear water 33075 34575 36075 37575 39075 40575 42075 43575 45075 46575 48075 49575 51075 52575 Mass of naphthalene applied (g): 2 . 00 g mass of unknown solute B (g): 0. 20 g Table 1 . several. Data in freezing point depression of naphthalene. Mass of naphthalene used (g)2. 0 g Mass of unknown solute A used (g)0. 20 g Mass of solution (g)2. 20 g Freezing stage of genuine naphthalene (oC)75 oC Abnormally cold point of solution (oC)73 oC Very cold point big difference of pure naphthalene along with solution (oC) Molality of solution (mol/kg) Moles of solute applied (mole) Molecular mass of solute (g/mole) Table 1 ) 4. Synopsis of data about boiling points of solutions with varying numbers of solute. Group No . Sum of solute B utilized (g)Boiling stage (oC) , 100 15. 5099. 0 21. 0090. 0 23. 5099. 5 42. 0099. 5 52. 50100 Versus. DISCUSSION?? NI. CONCLUSION? VII. LITERATURE CITED/BIBLIOGRAPHY