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Flashcards in Surfactants Deck (16)
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1

What is a surfactant?

Surface + active + agent

2

Phase boundaries..
Interface:

boundary between two phases

3

Phase boundaries..
Surface:

boundary between two phases, one of which is a gas

4

Energy is..

the capacity to do work

5

Surface energy..

potential energy per unit surface area

6

What does intermolecular bonding do to molecules?

Intermolecular bonding stabilises molecules and lowers their energy.

7

Surface tension...

energy required to expand the surface of a liquid by a unit area (N m−1 or dyn cm−1).

8

For liquids, surface tension and surface energy are...

quantitatively equivalent and often used interchangeably.

9

What do surfactants do?

reduce suface tension

10

Contact angle is...

Indicator of solid surface wettability

11

Wettability is...

Tendency of liquid to adhere to solid surface

12

Amphiphilic means..

has both hydrophilic (water-loving) and hydrophobic (water- hating) portions in the same molecule.

13

Uses of surfactants (3)

wetting agent

emulsifying agent

foaming agent

14

Micelles form when...

When the liquid surface is saturated with surfactant molecules, excess surfactant molecules sink below the liquid surface and self-aggregate into micelles.

15

Critical micelle concentration (CMC)

Minimum surfactant concentration at which micelles begin to form.

Generally, the larger the surfactant molecule, the lower the molar CMC.

16

What is Traube's rule?

Molar concentration of surfactant needed to achieve a certain surface tension decreases by ~3 fold with each —CH2 unit within a homologous series.