Journal of Colligative Properties

Journal of Colligative Properties

Alis Rahmawati

Colligative Properties

The Effect Kind of Solution to the Boiling Point

Alis Rahmawati / 113194213

Alis Rahmawati1, Anisah

2, Syifa Salima

3

International Chemistry Education 2011, FMIPA, Unesa

abstract

The research described in this paper is to know the effect kind of solution to the boiling point base from the

basic theory that have learn before, The research was carried out with experimental method at Wednesday,

4th

April 2012 in Basic Chemistry Laboratory of Unesa. In this Experiment, we prepared water in the some

beaker glass and then we boiled the water and measured the boiling point temperature of the water, after that we

added some sugar and salt with the different mass to the beaker glass and measured the boiling point

temperature of the solution. The result indicated that the boiling point of the water and the boiling point of the

solution was quite different with the theory that have been learn. Finally we can conclud that the different result

because of many factor that effected the boiling point like pressure, temperature, kind of solute and solvent, etc

KEY WORDS : coligative properties, sugar solution, salt solution, boiling point temperature

Introduction

Background of the study

Colligative Properties is one from many important subject in chemistry learning, so all of

student must understand well about this material. To can understand the material, student

must know the factors that include in this subject and they have to prove the theory to

understand well. To do that we can through experiment method. But in this experiment, we

just focus to the boiling point.

Statement of the Problem

The study intents to obtain answer to the following questions:

1. Prove or not that added of the sugar and salt can increase the boiling point?

2. What kind of matter that effect the boiling point of the solution?

Coligative properties (or collective properties)

are properties that depend only on the number of solute particles in solution and not on the

nature of the solute particles. The properties are bond together by a common origin – they all

depend on the number of the number solute particles present, regradless of whether they are


Alis Rahmawati

atoms, ions, or molecules. The colligative properties are vapor-pressure lowering, boiling-

point elevation, freezing-point depression, and osmotic pressure.

Boiling-Point

The boiling point of a solution is the temperature at which its vapor pressure equals the

external atmospheric pressure. Because the presence of a nonvolatile solute lowers the

pressure of a solution, it must also affect the boiling point of the solution. Figure 1 shows the

phase diagram of the water and the changes that occur in an aqueous solution. Because at

any temperature the vapor pressure of the solution is lower than that of the pure solvent

regadless of temperature, the liquid-vapor curve for the solution lies below that for the pure

solvent. Consequently, the dhased solution curve untersects the horizontal line that mark P =

1 atm at higher temperature that the normal boiling point of the pure solvent.

∆Tb = Tb – T0

b

Since Tb>T0b, ∆Tb is the posotive quantity

Boiling point elevation of nonelectrolyte solution

∆Tb ∞ m

∆Tb = Kb m

Where m is the molality of the solution and Kb is the molal boiling-point elevation constant.

The unit of Kb are 0C/m. It is important to understand the choise of concentration unit here.

Figure1.

phase diagram ilustrating the

boiling point elevation and the

freezing point depression of

agueous solution. The dashed

curves pertain to the solution, and

to the solid curves to the pure

solvent. As you can see, the boiling

point of the solution is higher than

that the of water, and the freezing

point of the solution is lower than

that of water.


Alis Rahmawati

We are dealing with a system (the solution) whose temperature is not conctant, we so can not

express the concebtration units in molarity because molarity changes with temperature.

Table 1 lists values of Kb for several common solvents. Using the boiling point elevation

constant and equation, we can see taht the molality m of an aqueous solution is 1.00, the

boiling point will be 100.520C

Boiling Point of Electrolyte solutions

The colligative properties of electrolyte require a slightly different approach than the one

used for the colligative properties of nonelectolytes. The reason is that electrolytes dissociate

into ions in solution, and so one unit of an electrolyte compound separates into two or more

particles when it dissolve. For example, each unit of NaCl dissociates into two ions Na+ and

Cl-. Thus the colligative properties of a 0.1 m of solution NaCl should be twice as great as

those of a 0.1 m solution containing a nonelectrolyte, sucs as sucrose

To accound for this effect we must modify the equations for colligative properties as follows

∆Tb = iKbm

The varieble i is the Van’t Hoff factor, which is defined as

i = actual number of particles in soln after dissociation

number of formula units initially dissolved in soln

thus i should be 1 for all nonelectrolyte.


Alis Rahmawati

Method

Research design

Tools and materials:

1) Beaker glass 100 mL

2) Tripod and kasa

3) Thermometer

4) Spirit

5) Aquades

6) Salt (NaCl)

7) Sugar (C12H22O11)

Variabel Control: mass of water 25 mL, zise of beaker glass, termometer, fire

Variabel Manipulation : the mass of material that added to the water and the kind of the

matter

Variabel Respond : The boiling point temperature

Procedure : The experiment boiled water in some beaker glass and then we added sugar and

salt with the different mass to the beaker glass. Beaker glass 1A we added 25

mL water and 3,42 grams of sugar. 1B added by 25 mL water and 6,84 grams of

sugar. 1C added by 25 mL water and 10,26 grams of sugar. 1D added by 25 mL

water and 13,68 grams sugar. And beaker glass 2A added by 25 mL water and

0.58 gram of salt. 2B added by 25 mL water and 1,17 grams of salt. 2C added

by 25 mL water and 1,75 grams of salt. 2D added by 25 mL water and 2,35

grams of salt. Finally,measured again the boiling point temperature of each

solution.

Result

Based from our experiment we got result of the boiling point temperature were:

Non electrolyte solution

1A 25 mL water and 3,42 grams of sugar was 970C

1B 25 mL water and 6,84 grams of sugar was 970C

1C 25 mL water and 10,26 grams of sugar was 970C – 98

0C

1D 25 mL water and 13,68 grams sugar was 970C – 98

0C


Alis Rahmawati

Electrolyte solution

2A 25 mL water and 0.58 gram of salt was 960C

2B 25 mL water and 1,17 grams of salt was 970C

2C 25 mL water and 1,75 grams of salt was 980C

2D 25 mL water and 2,35 grams of salt was 970C

Theory calculation

Known : volume Aqueous = 25 ml

Kb Aqueous = 0.520C/m

T0

b = 1000C

massC12H22O11 1 = 3.42 grams




mass NaCl 1 = 0.58 grams




i NaCl = 2

calculation

1. Boiling point of C12H22O11 3.42 grams

CCCT

TTT

mmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

0

2

208.100208.0100

208.04.0/52.0

4.025

1000.

342

42.3

1000.

2. Boiling point of C12H22O116.84 grams

CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

416.100416.0100

416.08.0/52.0

8.025

1000.

342

84.6

1000.


Alis Rahmawati


CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

624.100624.0100

624.02.1/52.0

2.125

1000.

342

26.10

1000.


CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

832.100832.0100

832.06.1/52.0

6.125

1000.

342

26.10

1000.

1. Boiling point of NaCl0.58 grams

CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

42.10042.0100

42.042.0/52.0

42.025

1000.

5.58

58.0

1000.


CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

832.100832.0100

832.08.0/52.0

8.025

1000.

5.58

17.1

1000.


CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

248.101248.1100

248.12.1/52.0

2.125

1000.

5.58

75.1

1000.


CCCT

TTT

CmmCmKT

mm

OmassHMr

massm

b

bbb

bb

000

0

00

2

67.10161.1100

67.161.1/52.0

61.125

1000.

5.58

35.2

1000.

Compare with the result from the theory,

Table 1 : the different result between theory and experiment

No nonelectrolyte(C12H22O11)

grams

base from the theory base from the experiment

Tb0 (

0C)

25mL H2O

Tb (0C) Tb

0 (

0C)

25mL H2O

Tb (0C)

1A 3,42

100 100.208 94 96

1B 6,84

100 100,416 94 96

1C 10,26 100 100,624 96 97


Alis Rahmawati

1D 13,68

100 100,834 96 97

electrolyte(NaCl)

grams

base from the theory base from the experiment

Tb0 (

0C)

25mL H2O

Tb (0C) Tb

0 (

0C)

25mL H2O

Tb (0C)

2A 0,58

100 100,42 95 96

2B 1,17

100 100,832 95 97

2C 1,75

100 101,248 97 98

2D 2,35

100 101,67 96 97

From the theory we got result that boiling point of pure water is 1000C and the boiling point

of the sugar and salt solution increase continuously depend with the mass (number of solute

particles). Between non electrolyte and electrolyte solution have different result although

both of them have same numbers of particles.

Moreover the result between theory and the experiment are quite different, all of the boiling

point of pure water and the boiling point of solution in the experiment result were below of

the theory result. Result of the boiling point solution itself unconstant although it is

electrolyte solution or non electrolyte solution, they did’t have differences.

Discussion

Boiling Point Elevation

Base from the table 1, we know that the experiment result was quite different with the result

from theory calculation. And between electrolyte and non electrolyte solution itself don’t

have different, it can to be like this because:

In this experiment had a lot of mistake:

1. We can’t control the variable control exactly like the fire strange from the burner so the

result from the same amount of particles don’t have same result.

2. When measured the temperature we must opened the cup, so the water and the solution

lose their Calor.


Alis Rahmawati

3. We did’t open the cup at same time so the temperature of the surrounding not same and it

gives contribution in boiling point. Because A liquid boils at the temperature at which its

vapor pressure equals atmospheric pressure. So the temperature of the surrounding doesn’t

constant

Although, many factor that can effected the boiling point

1. Pressure, different place have different pressure so the boiling point of the water and the

solution will depend with the pressure of the surrounding

2. Room temperature, different room temperature will make different pressure

3. Kind of the solute, have different number particle

4. Kind of the solvent, have different number particle

The solution can't boil at the same temperature as the pure solvent. If the vapor pressure of

the solvent escaping from the solution is smaller than the vapor pressure of the pure solvent at

any given temperature, the solution must be heated to a higher temperature before it boils.

The lowering of the vapor pressure of the solvent that occurs when it is used to form a

solution therefore increases the boiling point of the liquid.

The change in vapor pressure that occurs when a solute dissolves in a solvent leads to

changes in the melting point and the boiling point of the solvent as well. Because the change

in vapor pressure is a colligative property, which depends only on the relative number of

solute and solvent particles, the changes in the boiling point and the melting point of the

solvent are also colligative properties.

Conclution

According to the theory of colligative properties, the boiling point of water is 1000C. but the

result of our experiment did not show the same value because we did the experiment in low

surface area that have high pressure (more than 1 atm) so the boiling point is less than the

normal boiling point of water (boiling point at 1 atm). And for other solution the boiling point

will decrease too.

And the boiling point of electrolyte solution is higher than the non electrolyte solution.

Because the electrolyte solutions have more particles than the non electrolyte solution, The


Alis Rahmawati

reason is that electrolytes dissociate into ions in solution, so one unit of an electrolyte

compound separates into two or more particles when it dissolve. And according to our

experiment, the boiling point of NaCl (salt) solution is higher than C12H22O11 (sugar)

solution. It means that the boiling point of electrolyte solution is higher than non electrolyte

solution certainly.

Refferences

Tim kimiadasar. 2012. PenuntunPraktikum Kimia DasarLanjut. Surabaya: Unesa Press

Chapin, William H. 1949. Second Year College Chemistry 5th

edition. New York : John

Wiley & Sons, Inc

Chang, Raymond. 2004. Kimia Dasarkonsep-konsepintiedisiketiga.Jakarta :Erlangg

Sugiarto, Bambang.dkk. 2011. Basic Chemistry II handout.

Journal of Colligative Properties

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