Definitions Flashcards
Define the common terms in Acid and Base chemistry
What is a Bronsted acid?
proton donor
What is a Bronsted base
proton acceptor
expression of ph
Ph = -log[H3O+]
calculate Ph concentration
10^-pH
Define conjugate base?
It is the species left behind after a bronsted acid has transeferred a proton
Define a conjugate acid
It is the species formed after a base accepts a proton
What do you call a species that can both donate or accept protons?
Amphiprotic
What do you call a species that can donate more than one proton?
polyprotic
Define monoprotic acid
It is an acid which can donate ONLY one H+ (proton) to water eg. HCl
Define diprotic acid
It can donate up to two protons (H+) to water eg. H2SO4
define triprotic acid
It can donate up to three protons to water eg. H3PO4
What is Ka?
Acid disscociation constant / or acid ionization constant
What is the expression for Ka?
Ka = [A-] *[ H3O+]/ [HA]
What is the expression for pKa?
pKa = -log (Ka)
What factors are the strength of an acid dependent on?
charge of A
electronegativity of A
the strength of an HA bond
the extentof the delocalisation of of the negative charge on the anion A-
What is the autoprotolysis constant of water defined by?
Kw = [H3O+] [OH-]
water reacting by itself
In pure water is [H3O+] = [OH-] ?
yes; Kw = square root of Kw
What does the Henderson Hasslebach equation state?
pH = pKa + log 10 (A- aq/HA aq)
What is a titration?
A method of volumetric analysis used for determining the concentration of an uknown solution by letting it react with another
What is the equivalence point?
It is the volume at which the reaction is just completed. In an acid base titration, the pH changes most rapidly at the equivalence point
In a titration C1V2 = C2V2 at equivalence point
…
Where is the buffer region in a titration involving a weak acid and a strong base
around half way to the equivalence point; at this point ph= pka
In a titration involving a weak acid a strong base, what is the pH at equivalence point dependent on?
the pka of the acid and the concentration
What is an indicator?
A substance that has different colors in the acid and basic solution
What is the indicator usually? is it a weak acid?
yes
Where does an indicator change color most rapidly
When pH = Pkln
What is Kln?
the acid dissociation constant of that indicator
What is the best choice for an indicator?
an indicator whose color changes occurs at the pH of the equivalence point of the titration
What is a buffer solution?
a solution whose pH changes much less than that of pure water as we add either acid or base
What does a buffer solution typically contain?
approximately equal concentrations of a weak acid and its conjugate base, and its pH is the pKa of the acid
How does a zwitterion result?
is the result of an internal proton transfer, such as +NH3CH2CO2-
What is the isoelectric point?
the pH at which the majority of the species is the a zwitterion
What is electrophoresis?
is the separation of mixtures of amino acids based on their different isoelectric points
Acid rain? How does it arise?
arises when gases like SO2, SO3, NO2, etc… are dissolved in rainwater
What does it mean by the levelling effect of the solvent?
H3O+ is the strongest acid, and OH- is the strongest base, that can exist when water is the solvent
What is a superacid?
It is an acid stronger than pure sulfuric acid
What is a superbase?
is a very strong base
What happens to the conjugate base of an acid?
it loses an H+ and gains a one more negative charge?
What happens to the conjugate acid of a base?
It gains a proton and gains one more positive charge
