Chemistry for Biologists (part 2)

Water (H₂O)

Polar molecule

Cohesion

Tendency for water to stick to itself

• important for transpiration

Adhesion

Tendency of water to stick to other substances

Capillary action

Cohesion + Adhesion

Surface tension

A result of cohesion of water molecules

High Heat Capacity

• More hydrogen bonds cause a higher heat capacity

• Ability of a substance to resist temperature changes

• Allows constant body temperatures

Heat of vaporization

The heat a liquid must absorb for 1 gram to be converted to gas

Evaporative Cooling

Liquids evaporate, and the surface cools

Expansion on Freezing

• Lattice structure of ice causes water to expand on freezer

• This causes it to float, and allows animals to live beneath the ice

Solution

A liquid that is a homogenous mix of substances

Solvent

Dissolving agent of a solution

Solute

Substance that is dissolved

Aqueous solution

Solution where water is the solvent

Polarity

Makes water, a polar molecule, a versatile solvent

Hydrophobic

Substances do NOT dissolve in water (

Hydrophillic

Substances will dissolve in water

Acidic Solutions

Contains a lot of H⁺

Basic (alkaline) Solution

Contains a lot of OH^-

Acids

1-7 pH

Bases

7-14 pH

Buffers

Mantain stable pH