Introduction

The intent of this experiment is to mensurate and enter the surface tenseness of H2O and other aqueous solutions utilizing capillary rise method techniques and practising lab safety. In this research lab the surface tenseness of H2O depends on the concentration of the undermentioned solutes ; NaCl. propanone. and sodium dodecyl sulphate ( SDS ) . Intermolecular interactions every bit good as other stages ( solid. or air ) make a liquid exist. The information collected will demo that the surface tenseness of the liquid is relative to its equilibrium. Surface tenseness of H2O dependent on concentration of NaCl. SDS. propanone. and distilled H2O all have different consequences. The different radius consequences are a effect of the liquids surface tenseness and therefore its intermolecular spherical forms

Background

The surface tenseness of a liquid depends on the belongingss of the liquid. For illustration. H2O is affected by the stages it comes into contact with ( solid. air ) . A cylindrical tubing is used to mensurate a liquids surface tenseness. Hydrostatic force per unit area of a liquid is equal to the force per unit area difference across the semilunar cartilage. An isotropic province is when other such molecules surround a mass of molecules in a pure liquid. A molecule that is non surrounded by many molecules is considered to be at the surface boundary.

Procedure

For the first measure five to six solutions of NaCl that range in concentration signifier 0. 1 to 0. 4M is weighed. prepared and set aside. Following five to six solutions of propanone and H2O with molar concentrations up to 1. 0M were besides prepared and set aside. Finally a solutions of SDS with molar concentrations of 2?1. 0 -4 M. 4?10 -4 M. 8?10 -4 M. 2x 1. 0 -3 M. 4?10 -3 and 8x 10 -3 was massed. To obtain accurate consequences the setup was taken under the goon and flushed with chromic acid a figure of times so cleaned with distilled H2O. The capillary tubing was so secured to a base with a clean little pipet bulb to the top terminal of the tube and prepared for the first reading. 100 milliliter of the first liquid was placed in a 150 milliliter beaker and its temp was taken. After the setup was assembled and the 0 grade on the graduated table should be degree with the surface of the H2O. a arrow is used to read the graduated table and the location of the semilunar cartilage.

Once the setup is ready a bulb is used to coerce the liquid through the capillary tubing no higher than 10-cm. This portion of the process was repeated a figure of times to guarantee an accurate semilunar cartilage reading for each liquid. The semilunar cartilage was the recording to find the surface tenseness of the liquid. Rinsing the setup with distilled H2O between each liquid will avoid cross taint.

Consequences

The mean semilunar cartilage of merely distilled H2O was 3. 44m. Additionally. the surface tenseness of H2O is 72. 8? table 1 illustrates the weights. capillary rise ( H ) which is measured in millimeter. molar concentrations ( M ) and densenesss ( P ) of Nacl. propanone and SDS. The undermentioned equation was so used to find radius and compare the surface tensenesss of the different liquids to pure distilled H2O: P g H = 2 ?/r. ( 1 ) ( 3. 44 ) ( 9800 ) =7. 29?2. r= 4. 31?10 -4. The consequences were so plotted on a graph in order R

to visualise the differences. The information graphed showed that there is a relative relationship between the addition of molar concentrations and surface tenseness. Harmonizing to the graphs the surface tenseness ( y-axis ) and the morality ( x-axis ) of the liquids determine the common solubility’s.

| |Capillary rise ( H ) NaCl ( millimeter ) |Density ( P ) NaCl ( g/mL ) |NaCl ( M ) | | |4. 1 |2. 3376 |0. 4 | | |4. 35 |1. 7532 |0. 3 | | |4. 47 |1. 1688 |0. 2 | | |5. 2 |0. 5844 |0. 1 | |Average |4. 53 |1. 461 | | |Surface Tension ( Y ) Acetone |Surface Tension ( Y ) SDS |Acetone ( M ) | |11. 98993211 |0. 016008202 |0. 25 | |21. 09737414 |0. 02787708 |0. 5 | |28. 70224157
|0. 03041136 |0. 75 | |Average |45. 01590878 | |1 |

|Density ( P ) SDS ( g/mL ) |Surface Tension ( Y ) SDS |SDS ( M ) | |0. 002 |0. 016008202 |0. 002 | |0. 004 |0. 02787708 |0. 004 | |0. 008 |0. 03041136 |0. 008 | | | | | |Average |0. 004666667 | | |

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Discussion

In the literature it is stated that the surface country adopts a spherical form in the absence of gravitative or other substances. Therefore. it has the lowest surface to country volume ratio. Additionally. the surface are to the volume of a domain is smaller than that of a regular hexahedron. The domain has a radius ( R ) and the volume is represented mathematically as 4/3 ? r3 and the surface country 4?r2. However. a regular hexahedron with the same volume=r? ( 4/3? ) 2/3 and a surface country 6?r2? ( 4/3? ) 2/3 which is about equal to 15. 6 and is bigger than 12. 6.

A spherical form has a entire minimum surface country. The different forms are present because as the molar consintrations increased the surface tensenesss increased every bit good. The inclines of the graphs are all in the positive way. SDS is a surfactant and hence really small SDS is necessary to blend with H2O the graphs show that there is more NaCl nowadays in the mixtures when compared to the SDS. Additionally. the NaCl is needed in much more sums and this is clear on the graph.

Decision

At first glimpse it appears that the semilunar cartilage readings for NaCl are much higher than both the propanone and SDS. This is because less SDS is necessary to bring forth a mixture with H2O. Sing this information it can be inferred that the surface tenseness of NaCl is higher and hence the sum of work required to increase its surface country is higher every bit good. Finally. it was determined that as the molar concentrations increase the surface tensenesss addition every bit good.

Mentions

[ 1 ] Arthur M. Halpern. George C. McBane. Experimental Physical Chemistry: A Laboratory Textbook. 3-rd Ed. . W. H. Freeman and Co ( New York ) . 2006.

[ 2 ] Peter Atkins. Julio dePaula. Physical Chemistry. 8-th erectile dysfunction. . W. H. Freeman and Co ( New York ) . 2006.