2 - Water, concentration, equilibrium constants, pH Flashcards
Define electronegativity
tendency of an atom to attract a bonding pair of electrons
Describe the bonding in a water molecule
- In a water molecule two hydrogen atoms form single polar covalent bonds with an oxygen atom.
- Oxygen is more electronegative than hydrogen, oxygen has a partial negative charge and the two hydrogen atoms have a partial positive charge.
Describe the shape of simple molecules in terms of hybridisation and lone pairs
Electronic configuration in water, H2O ‘sp3 hybridised’
Water dissociation constant Kw
10^-14 at 298 K
What is molarity?
moles of solute/liters of solution
Water Molecule Shape
Lone pairs (LP) repel each other more than bonding pairs, reducing bond angle to 104.5
effect of high boiling point
liquid at room temperature
Cohesion
Attraction between molecules of the same substance - one molecule drags the next up a tree
heat of vaporization
The amount of energy required for the liquid at its boiling point to become a gas
surface tension
the force that acts on the surface of a liquid and that tends to minimize the area of the surface
specific heat
The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius - water resists changing its temperature
universal solvent
Water- due to its polarity and ability to dissolve many different solutes
hydration shell
the sphere of water molecules around each dissolved ion
Oil drop effect
Water molecules next to hydrophobic molecules cannot satisfy H-bonding requirements, so are less stable.
To maximise number of H bonds which can be formed, clustering of non-polar molecules.
pH
hydrogen ion concentration
pH = -log[H+]
