Water Flashcards
Bonding in water
Oxygen is 1s2 2s2 2p4
Two unpaired electrons hydrogen has 2 lone pairs of electrons
Capable of forming a max
Hydrogen bonds form everywhere
Water
Hydrogen bonding to one another
Charge distribution
Electronegativity of oxygen
Molecules bent geometry give rise to a dipole
Dissociation
Constant motion Vibrations Stretching Shortening of a bond Closer together Instant
Cont
Bonds stretch so it forms new 0 h bond
Dative covalent
Creates 2 new species has electrical charge - hydroxonium ion
Cont
Dissociation auto ionisation
Abbreviated
Room temp
Reach equilibrium
Acid and bases
Acid - substance which hydrogen ions by dissociation
Hcl is strong acid dissociates in water
Physical states of substance are denoted by g - gas aw - aqueous
Cont
Bases which can extract proton
Free hydrogen ions
Bases dissociated in water m. Strong bases
Ammonia is weak base
Ph as measure of acidity
Molar conc of hydroxonium ions
Ph= - log10 [h]
Hydrogen ion conc in mol dm-3
Calculating ph of water
Degree of dissociation measure by equilibrium constant
Ratio concentration dissociated ions to the I dissociated molecules
Conc
Conc of water is constant as it equivalent to the density of water
Pure water exists in form of ions
Kw is constant at certain temp
Weak acid and bases dissociated in water
Weak acids partially with water gives hydroxonium ion weak base react to give hydroxide ions.
Dissociation is constant
Equilibrium constant for decomposition
Cont
Acid dissociation is constant, weak acid reaches equilibrium with conjugate base.
Base dissociation is equilibrium conjugate acid
Buffers
Metabolic cells results in production of acids
Lactic acid is produced in muscle tissue
Proteins a d enzyme required constant ph
Buffers
Blood has narrow limits
Minimise changes in ph
Resist changes
Mixtures of weak acids or bases and salts
Buffers
The water molecule and hydroxonium ion formed are conjugate acid base pair
Equal
Ph less than 7 is acid
Buffers
Base in form of hydroxide ion
Preventing the rise in ph
Henderhassel Bach
Composed a specific conjugate acid - base
Maintain through its buffering
Ha/a-
Life in water
Solids which easily dissolve in water form ions because they charged ion
Interact with polar water molecules
Organic molecule
Polar covalent bonds
Cont
Hydroxyl group is highly polar Strongly attracts water molecules The high solubility of sugars Organic molecules as alcohols Doubly bonded to an oxygen atom
Cont
Functional group are called carboxyl if acids Hydrogen is polar Hydrogen has free h ions Dissociating losing a proton to water Base in accepting the proton
Amino acids
Did sociable group Predominantly proton acted Physiological ph 7 Carboxyl group will dissociated Amino group will be protonated
Controlling cellular ph
7 is neutral
Radic effects on biological molecules
Organisms can control its internal ph
Buffer against ph changes
Summing up
Water is diplomolar which undergoes hydrogen bonding
Water forms hydroxonium ion
Biological buffers
Affect acidity App rotate rate Ph of the reaction medium can be controlled Groups of atoms Charged or neutral Has significant effect
Cont
Cells and the fluids surrounding the cells
Ph of blood is 7.35
To protect against ph change causes by acidic or basic metabolise
Cont
Unit is extreme
When a stress is applied to a system at equilibrium the system will adjust to relieve the stress - le Charliers principle
Cont
The dihydrogen phosphate / hydrogen phosphate system
Internal fluid of all cells
Hydrogen ion donor ( acid)
Hydrogen ion acceptor (base)
Cont
The ability of a compound to act as a buffer at a given ph
It will accept and donate protons
Buffers are most effective
Cont
The carbonic acid/ hydrogen carbonate system - blood plasma, equilibrium buffers ph