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Experiment 3SURFACE TENSION

Group # 3

Geofrey S. BajeCarlo James S. Banglagan

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I. ObjectivesTo determine the surface tensionvalues of a set of organic

samples and the effect of thedifferent concentration of

detergent on the surface tensionof tap water

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What is Surface Tension?

II. Introduction

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Surface tension is a phenomenonin which the surface of a liquid,

where the liquid is in contactwith gas, acts like a thin elastic

sheet. This term is typically used only when the liquid surface is in

contact with gas (such as the air).

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Surface Tension has significantimpacts on the survival as well as

the processes needed for day today existence of living beings.

Surface tension is also essential for the transfer of energy from

wind to water to create waves.

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CohesionAll the forces of attraction among

particles of a liquid.

Adhesion- Forces of attraction between a

liquid and another surface.

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III. Apparatus and Materials

Beaker (2pcs 50-mL, 2pcs 250mL)Graduated cylinder (100-mL)

Watch glass

DetergentHard glass test tube

Glass tubing

Capillary tubeRubber stopper

Rubber tubing

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Distilled WaterDensity1g/mL

Methanol

Density0.7918g/mLEthanol

Density0.789 g/mL

AcetoneDensity0.792.5 g/mL

Glycerin

Density1.261 g/mL

Organic Samples

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IV. Set-Up

Hard glass test tube

Glass tubing

Capillary tube

Cotton

Rubber stopper

Rubber tubing

Aspirator

Liquid sample

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V. Procedure1. Prepare the given set-up2. Clean the test tube and the

capillary tube so that notraces of grease will be left.

3. Add the liquid sample and

wait for the system to be at

equilibrium.

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4. Slightly raise the liquid by gently blowing into the

rubber tube and allow to fall back to its equilibrium level.

Then it is depressed by slight

suction and again allow tocome to equilibrium.

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5. Measure the difference in thelevel of the liquid in the

capillary tube and in the testtube. Read the bottom

meniscus and must be read 4

to 5 times to minimize errors.

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6. The radius of the tube is

obtained by observing the

capillary rise with pure

water, the surface tension of

which is known to be 71.8dynes/cm at 25C.

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The radius of the tube is obtainedusing the formula=rhg ( is

surface tension, r is radius, h is

height, is density and g is gravity)

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Sample calculation: Find r

=rhg

71.8dyne/cm=r(3cm) (1g/cm3)(980cm/s2)

r=4.88E-2 cm

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7. Repeat steps 1-5 using thefollowing liquid samples

Distilled water

Methanol

Ethanol

Acetone Glycerin

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8. Repeat steps 1-5 using the

following compositions of

detergent and tap water

a) 0.070g detergent with 20mlwater

b) a-10ml + 10ml waterc) b-10ml + 10ml water

d) c-10ml + 10ml water

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Thank You for listening 3ChE-B