Chem 6c

What is the Arrhenius definition?

acid - contains H, releases H3O+ into H2O

base- contains OH and releases OH- in H2O

What is the Bronsted-Lowry definition?

acid- proton H+ donor

base- proton H+ acceptor

Is water and acid or base

Water is both, amphiprotic: H2O +H2O → H3O+ + OH-

What’s a BL conjugate acid base pair

acid donates a proton (H+), species left w/o proton is called conjugate base

What makes Ka larger?

For same row: higher electronegativity of X

- For same group: larger radius of X

- For higher electronegativity of A

Oxoacids:

- For more Os attached to central atom

HBr(aq)

strong acid

HCl(aq)

strong acid

HI(aq)

strong acid

HNO3

strong acid

HClO4

strong acid

HClO3

strong acid

H2SO4 (to form HSO4-)

strong acid

Group 1 hydroxides (LiOH, NaOH, …)

strong bases

Group 1 hydrides (LiH, NaH, …)

strong bases

Ca(OH)2 , CaH2

strong bases

Sr(OH)2, SrH2

strong bases

Ba(OH)2, BaH2

strong bases

Group 1 and Group 2 oxides

strong bases

What is an oxide?

compound w atleast one oxygen

What are the applicable practical rules from 6b?

1. dissolved species enter as concentrations in moles per liter

2. pure solids and pure liquids appear in equilibrium expressions

strong acids have a ____ ka and ___pka

high ka and low pka

weak acids have a ____ ka and ___pka

low ka and high pka

strong bases have a ___ kb and a ____pkb

high kb and low pkb

weak bases have a ___ kb and a ____pkb

low kb and high pkb

What is Lewis theory?

acid- electron pair acceptor

base- electron pair donor

whats a basic solution

greater than 7

whats an acidic solution

less than 7

why is the stronger the acid, the weaker the conjugate base

more deprotonation occurs, conjugate base does not have the desire to gain a H+ and is a poor H+ acceptor → weaker base

Why is it that the stronger the base, the weaker the conjugate acid.

more protonation occurs, has larger radius, conjugate acid does not have the desire to lose a H+ and is a poor H+ donor → weaker acid

Acid strength in water depends on the breaking of the H – A bond and the formation of H2O – H+ bond. A stronger acid will …

bond that break H-A is very lose and the bond that forms H2O-H+ bond is strong

If A in H−A is very electronegative…

H−A bond is very polar, H has a large δ+ and can easily hydrogen bond to water, great chance of

deprotonating – stronger acid

in an oxide as the electronegativity of A increases…

electron density in the A−O−H shifts toward A away from H, O−H bond becomes more polar, Hydrogen is more easily deprotonated, increased acid strength

As the number of oxygen atoms increase…

more O atoms withdrawing electrons from the oxygen attached to the H, The O−H bond weakens which causes a greater chance for deprotonation therefore increased acid strength

cations can be

acidic or neutral

neutralization reaction btwn a strong base and weak acid forms

a basic salt

neautralization reaction btwn a weak base and strong acid forms

acidic salt

neutralization reaction btwn a weak base and weak acid

acidic,neutral, or basic salt

neutralization btwn a strong acid and strong base

neutral salt

conjucate base acts as a ____ for protons

sink

weak acid acts as a ____ for protons

source

steps to calculate inital choice of a buffer

select acid w pka close to required ph, prepare an equimolar solm w acid and its conj base (use salt), adjust ph of soln by changing concentration of acid and base using hasselbalch, to increase ph add base to decrease ph add acid

For strong acids and strong base titrations

v=0 strong acid

v= before equiv pt= strong acid

v= equiv pt= neutral

v= after equiv pt=strong base

for weak acid strong base titrations

v=0 weakacid

v= before equiv pt= bugger

v= equiv pt= weak base

v= after equiv pt=strong base

oxidation of an element uncombined with other elements is

0

oxidations numbers of all oxidation species is equal to

the total charge

oxidation of group 1 and 2 are

equal to their group number (except H is -1 w metals)

oxygen is ___ except when its in compounds w F or in peroxides, superoxides, and ozonides

-2

Oxidations if F is ___ (except when its 0)

-1

oxidation of all halogens are ___ unless in combo w O or another halogen

-1

oxidizing agent

species that causes oxidation and in process gets reduced, accepts e- for species being oxidized, contains an element w high oxidation state

Reducing agent

causes reduction and in process gets oxidized, supplies e- to species being reduced, contains an element w low oxidation state which becomes high oxidation state

oxidation, reducing agent, and substance oxidized

all cause oxidation number to increase and loss of e-

reductuin, oxidizing agent, and substance reduce

decrease in oxidation number, gain of e-

steps for balancing a redox rxn in acidic soln

1. identify species oxidizes and reduced using oxidation numbers

2. write both half reactions unbalanced

• balance all elements, balance o by adding H2O (l), balance H by adding H+(aq), balance charge by adding e-

3. multiply each entire half rxn to cancel out e- if needed

4. add half reactions to cancel like terms

steps for balancing redox rxns in basic soln

1. balance txn same as if in acidic soln

2. for every h+ leftover, add an OH- to form H2O, add same # of OH- anions on other side of rxn

3. remove same number of redudant waters on each side of the reaction