Water, concentration, equilibrium constants and pH

delta negative

slightly negative

electronegativity

tendency of an atom to attract electrons

higher electronegativity value ..

stronger attraction for electrons

tetrahedron

A pyramid with a triangular base.

tetrahedral angles in water

109.5

effects of hydrogen bonds

higher boiling point, cohesion, heat of vaporisation, surface tension, specific heat

heat of vaporisation

energy to convert 1g of water from liquid to gas at 25C

ice structure

crystalline lattic, 4 H bonds per molecule compared to 3.7 in water

specific heat

amount of heat absorbed or lost to change temp of 1g of water by 1C. specific heat of water is 1 calorie/g/C

hydration shell

sphere of water molecules around each dissolved ion

amphipathic

possesses both hydrophilic and hydrophobic regions

molecular mass

sum of masses of all atoms in a molecule

1 mole of a compound is

6.02 x 10^23 molecules - equivalent to its molecular mass in grams

1 molar solution =

1 mole/litre

what happens when hydrogen atom shifts from one water molecule to another

H+ left behind - results in an OH- and hydronium ion (H3O+)

acid

substance that increases H+ concentration of solution

base

substance that decreases H+ concentration of solution

buffer

substance that minimises change in H+ and OH- concentration by accepting/donating H+

pH

a measure of acidity/H+ concentration present in an aqueous solution