Surfactants and Non-Covalent Interactions

Flashcards about Surfactants and Non-Covalent Interactions

What is a colloid?

A substance dispersed in another where the two substances are not miscible.

What combination can't you get in a colloid?

Gas in Gas.

What type of colloid is ice cream?

Solid and gas in liquid.

What is the typical size range for colloids?

Between 1 nanometer to 1000 nanometers (1 micron).

What do surfactants, specifically phospholipids, do in colloids?

They provide stability to things.

What are the two different types of colloids?

Low phytic and Leo phobic.

What does 'Leo phytic' mean?

Solvent liking.

What does 'Leo phobic' mean?

Solvent hating.

Give an example of Lyo phytic colloids?

Polymers.

What is another title applied to colloids?

Association colloids formed by amphipathic molecules (like surfactants).

What is the key point about live colloids?

They are thermodynamically stable

What is an amphiphilic molecule?

A molecule with a hydrophilic (water-loving) part and a hydrophobic (water-hating) part.

What is a hydrophobic part typically?

A long alcohol chain.

What can the hydrophilic part be made of?

Ionic groups or hydrogen bonding.

What is the probably the most studied surfactant?

SDS (sodium dissolve sulphate).

What is SDS sometimes referred to as?

Sodium Laurel Sulphate

What percent is SDS in washing up liquid bottles?

20%

What makes a species a surfactant?

Surface active agents as they absorb interfaces and form oriented monolayers.

Give another behavior/characteristic of surfactants.

They self associate and make colloidal aggregates such as Mycelis.

What are some uses for surfactants?

Cleaning, lubrication, paint stabilization, salad dressing stabilization, waterproofing, etc.

How does detergent cleaning work?

Through a type of IT sorption process or by lowering the interfacial tension between water and the oil.

How does detergent cleaning work?

They stick to the oil droplets on your clothing, or lower the interfacial tension between the water and the oil, allowing oily stuff to be pulled off.

What do you need to make soap?

Animal fat, lye (NaOH), and heat.

How are surfactants classified?

Classified based on the hydrophobic tail and the hydrophilic head.

What are the classic head group classifications of surfactants?

Anionic, cationic, non-ionic, and zwitterionic.

What are the hydrophobic chain types of surfactants?

Silicone, fluorocarbon, and hydrocarbon chains.

Give an example of an Anionic Surfactant

SDS (sodium dodecyl sulfate) and sodium lauryl sulfate.

What makes cationic surfactants unique?

They adsorb well to surfaces with that slight negative charge.

What are cationic surfactants not good at?

They aren't good at cleaning.

What are cationic surfactants used for?

Anti-static agents, friction modifiers, fabric softeners, and hair conditioners.

Give an example of a Non-Ionic Surfactant?

Sugar surfactants, Polysorbates, and Polyethylene glycol.

What's the cool this about Non-Ionic Surfactants?

They tend to be really compatible with other types of surfactants.

Why is Non-Ionic Surfactants added to Laundry Detergent?

Helps with water hardness and allows for lower temperature washes.

What is a Zwitterionic surfactant?

Contains two different charges held apart by bonds (e.g., phospholipids).

What is special of Beatings, an example of a Zwitterionic surfactant?

pH sensitive and often found in kids' shampoo.

How is the Hydrophilic-Lipophilic Balance (HLB) calculated?

The ratio of head group size to the total size in terms of mass of the molecule, multiplied by 20.

What drives surfactants to do stuff?

Non-polar covalent interactions.

What are the different types of non-covalent interactions?

Electrostatic interactions, Hydrogen bonding, and dispersion forces (van der Waals forces, London dispersion interactions).

Describe electrostatic interactions

Interactions that are attractive between negative charges and repulsive between like charges; force is proportional to the charge and inversely proportional to the square of the distance.

Define Dipole Moment

The electrostatic potential of two opposite charges separated by a distance.

Define Polarizability

Describes how easily the electron distribution of a molecule can be distorted by an external electric field.

Define Dispersion Interactions

The force that induces two molecules with close contact to have synchronized charge fluctuation, and thus become attracted with short distance.

How is dipole moments expressed?

Expressed in Debye (D).

What is a dipole-induced dipole interaction?

This interaction involves a molecule with a dipole moment inducing a temporary dipole in a neighboring nonpolar molecule; stronger with greater polarizability.

What is the most attractive angle in interactions involving an interaction with trigonometric dependence?

Is zero at zero and 180 degress angles while has the maximum attraction at 90 degress and 270 degress