Lesson 2.1. Pre-Lab: Surface Tension

Surface tension

Force per unit length that must be applied parallel to the surface area so as to counterbalance the net inward pull

drop weight method

Surface Tension is measured using the ___________________

surfactants

Surface Tension is reduced by adding __________

anionic, cationic, non-ionic and amphoteric

In Surfactants, it can be categorized according to its chemical properties:

hydrophilic

In surfactants, the higher the HLB value the more ______________

Surfactants

used as a wetting agent, solubilizing agent, and emulsifying agent

emulsiom

• should contain a relative amount of emulsifying agents in order to produce a physically stable

• relative amount can be computed using the HLB values

Required Hydrophile-Lipophile Balance (RHLB)

Oil phase of an emulsion requires a specific HLB called the ___________

drop weight method

Determine the relative surface tension of a liquid, compared to a standard (water)

surface tension of the sample

Y1 = ?

surface tension of the standard

Y2 = ?

mass of the sample

m1 = ?

mass of the standard

m2 = ?

m = wt./no. of gtts

formula for the mass in the drop weight method

Stalagmometer

glass instrument designed to measure the surface tension of liquids by counting drops that fall from its capillary tip

1-3

HLB NUMBERS:

• anti-foaming agents

4-6

HLB NUMBERS:

• water-in-oil emulsifier

7-15

HLB NUMBERS:

• wetting agent

8-18

HLB NUMBERS:

• oil-in-water emulsifier

10-15

HLB NUMBERS:

• detergent

10-18

HLB NUMBERS:

• solubilizer