Chem 123 unit 1

acida and bases

bronsted lowry acid

proton donor (HA)

Brondsted lowry base

proton acceptor (A-)

Conjugate acid and base pair

pair of chemicals that only differ by one proton

reactant quotient (Q)

ratio of products/reactants

for any reaction that occurs in both the forward and backwards reaction at ANY given moment in time

equilibrium constant (K)

the ratio of products/reactants at EQUILIBRIUM

only one k value for every reaction, differs for all reactions

if a system is at equilibrium then…

Q=K

reaction is at its most stable

acid and base reactions are….

thermodynamically controlled

strong acids

acids that dissociate to completion

HCL, HBr, HI, HClO4, HNO3, H2SO4

strong acids have a large K(a) value ( means that the reaction favours the products)

Weak acids

partially dissociate in a reaction

smaller K(a) value- reactants are more stable than products

CH3COOH

Strong Bases

dissociate to completion

NaOH, KOH, Ca(OH2) - any group 2 with OH

larger Kb value- products are more stable

Weak Bases

partially dissociate in a reaction

Kb is small- favours the reactants

NH3- ammonia

amphoteric

the ability for a compound to act both as an acid and a base depending on what it is reacting with

ex: water

properties of water

Kw= 10 ^(-14)

pH +pOH= 14

pH = 7

pOH= 7

Buffers

solutions that resist changes in pH when an acid or base is added to the reaction

They stabilize the pH by neutralizing H3O+ or OH-

consists of a WEAK conjugate acid and base pair

buffer ratio

HA/A = within 10x of eachother

anytime there are conjugate acids and bases…

K(a) + K(b) = K(w) = 10^(-14)

pKa

-logKa

acid dissociation constant

pKb

-logKb

base dissociation constant

claculatin pH of a salt solution (quantitative)

- split salt into cations and anions
2- determine which is the spectator ion
3- determine how the cation or anion will react with water
4- caluclate pH based on concentration of H3O+ or OH-

determining wether a salt sollution os acidic or basic (qualitativ)

1- split salt into cations or anions
2- add H to anion, remove H (or add OH) from cation
3- consider the strengths of the acids/ bases present

weak acids reacting with weak bases

dont fully dissocossiate in water
to find concentrations of products use

K(a/b) = x^2/(concentration of acid/base)

strong acids reacting with strong bases

products = mole coeficient (limiting reagent)