Lecture 3: Chemical Bonds and Water

Solution

homogeneous mixture of substances

Solvent

dissolving agent of solution

Solute

substance that is dissolved

Aqueous Solution

water is the solvent

- water is versatile solvent

Hydration Shell

ionic compound is dissolved and each ion is surrounded by sphere of water molecules

Hydrophilic

polar

- dissolve in water

- has to have charge or partial charge

Hydrophobic

nonpolar

- cannot dissolve in water

- oil molecules

Water

polar and ionic bonds dissolve

- can interact with full or partial positive charges

Autoionization

- water splits, oxygen steals an ion from hydrogen

- either left with H+ (just proton) or OH- (gain electron)

- determines if substance is acidic or basic

Neutral Solution

Equal H+ and OH-

Acidic Solution

More H+

Basic Solution

More OH-

pH scale

acidic: < 7

basic: > 7

- most biological fluids have pH around 6 to 8

Buffers

substances that minimize changes in concentrations of H+ and OH-

- contain weak acid and its corresponding base