Senior Science Flashcards
List a few chemicals used in everyday life (3)
Cleaner - emulsifies
Lubricants - reduces friction
Cosmetics - slows water loss
What is the tyndall effect?
Light that is visible passing through a…colloid/suspension
List mixtures according to particle size:
Small - solutions
Medium - colloids
Large - suspensions
Provide an example of each mixture (solution, colloid, suspension)
Solution - soft drink
Colloid - milk
Suspension - flour suspended in water
What is a solution?
Dissolved particles, uniformly distributed
What is a colloid?
Particles that are suspended, do not filter but settle
What is a suspension?
Particles that separate over time, can be filtered
List 4 types of colloids
Emulsions
Foam
Sol/gel
Aerosol
What is an emulsifier?
Substance that allows dispersion of liquids
Define surface tension
Forces between molecules in a liquid, pulling them inward
Define miniscus
Shape that the surface of a liquid takes in a tube
How does a surfactant work?
Where a molecule dissolves into an oil substance, REDUCING SURFACE TENSION
Define the purpose of an emulsion
Dispersion of droplets of one liquid into another which are not soluble
Define biodegradable
Substance that can be broken down by living organisms
Why is skin classified as an organ?
Because it contains a minimum of two tissues working together
Where are new cells made?
Low layerm of epidermis
Functions of the skin?
- Heat regulation
- Protection
- Excretion
- Sensation
- Immune response
What is the purpose of micro-flora on the skin?
Mutualism occurs as micro-flora break down sebum into fatty acids to maintain the slight acidity of the skin
What are the 2 most commonly used solvents and why?
Water - due to polarity of water allows greater attraction and dissolving
Ethanol: It contains carbon atoms and is ‘organic’
For a drug to be effective it must…
- Reach target at correct doasage
- treat
- last long to take effect
- only affect tissues designed for
- have few side effects
What is the pH of the skin, mouth, stomach and small intestine?
Skin: 5.5
Mouth: 8
Stomach: 3
Small Intestine: 9
What are two types of tablets?
Enteric-coated
Slow-release eg. Osmotic pump