Biochemistry Chapter 3-AP Bio Part 3 Flashcards
Hydrogen ion (H+)
A single proton with a charge of 1+
What happens occasionally to a hydrogen atom participating in a hydrogen bond between TWO water molecules
The hydrogen atom shifts from one molecule to the other, leaving its electron behind
Hydroxide ion
(OH-) the water molecule that lost a proton that has a charge of -1
Hydronium ion
The proton that binds to the other water molecule.
H+ does not what
Exist on its on in an aqueous solution, always associated with H3O+
Dynamic equilibrium
When water molecules disassociate at the same rate that they are being reformed from H+ and OH-. At this point the concentration of water greatly exceeds the concentrations of H+ and OH-.
The dissociation of water is __________________
Reversible and rare
H+ and OH- are extremely ____________
Negative
What can changes in H+ and OH- result in
Drastically affect a cell’s proteins and other complex molecules.
What happens when acids dissolve in water
They donate additional H+ to the solution
Acid
A substance that increases the hydrogen ion concentration of a solution
Acidic solution
A solution having more H+ than OH-
Base
A substance that reduces the H+ concentration of a solution
How to bases reduce H+ ion concentration
Directly by accepting hydrogen ions or indirectly by dissociating to form hydroxide ions, which combine with hydrogen ions and form water.
Weak acids
Acids that reversibly release and accept back hydrogen ions.
pH
The negative logarithm (base 10) of the hydrogen ion concentration
pH _________ as concentration ____________
Declines, increases
A solution of pH 3 is not twice as acidic as pH 6
but (10 x 10 x 10) more acidic
Buffer
A substance that minimizes changes in the concentration of H+ and OH- ions by accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solution when they have been depleted.
Carbonic acid
A buffer formed when CO2 reacts with water in blood plasma. Dissociates to yield a bicarbonate ion (HCO3-) and a hydrogen ion (H+)
The chemical equilibrium between carbonic acid and bicarbonate acts a
pH regulator
What happens if the H+ concentration in blood begins to fall
The reaction proceeds to the right and more carbonic acid dissociates, replenishing hydrogen atoms
What happens if the H+ concentration in blood begins to rise
The reaction proceeds to the left, with HCO3- (the base) removing the hydrogen ions from the solution and forming H2CO3.
Carbonic acid-bicarbonate buffering system consists of
an acid and a base in equilibrium with each other.
Most buffers have
Acid base pairs
What happens when CO2 dissolves in seawater (ocean acidification)
It reacts with water to form carbonic acid which lowers the pH of the ocean
What happens as seawater acidifies
The extra hydrogen ions combine with carbonate ions to form bicarbonate ions,,,reducing the carbonate ion concentration.
