exam 3 Flashcards
Alpha particle
α
nucleus loses 2 protons and 2 neutrons, total: 4 nucleons
Beta particle
β
- atomic # increases by 1 proton
- 0 nucelons but - 1 charge
Positron particle
- behave like electron but w/ positive charge
- atomic # decreases by 1 proton
- 0 nucleons but + 1 charge
What does equilibrium mean?
- when a rxn and its reverse rxn proceed at the same rate
- both fwd and reverse rxn’s are occuring
Equilibrium constant
Kf / Kr = Keq (no units)
- depends only on temp
What is heterogeneous equilibria?
when/if one or more reactants or products are in a different phase
What do we exclude from K expression? (pure liquids, gasses, aqueous, solids)
Pure Liquids and solids
what is K for a fwd rxn of:
2SO₃ <=> 2SO₂ + O₂
Kf= [SO₃]²
When you multiply reaction by a number, what is done to get new K?
(K)^’
When two reactions are added, what do you do to get new K?
A + B + C = C + E
Equalssssssss
A + B = E
Kc VS Kp?
Kc: concentration-based eq. constant
ex. = [B]^b / [A]^a
Kp: pressure-based eq. constant (for gases)
ex. = (Pᴅ)ᵈ / (Pc)ᶜ
Le chateliers principle:
- any change to chem. system @ eq. causes the rxn to proceed in direction that reduces stress caused by change
Effect of change in concentration:
Keq > Q … shift RIGHT
- increased reactants
Keq < Q … shift LEFT
- increased products
Arrhenius acids: definition
- substance that when dissolved in water increases the concentration of hydrogen ion H+ (H3O+)
- typically end in -ide, -ate, or -ite
Arrhenius bases:
- substance that when dissolved in water increased concentration of hydroxide ion
- typically end in hydroxide (OH-)
Bronsted-lowry acids
proton donor!
must have removable acidic proton
Bronsted-lowry bases
proton acceptor!
must have a pair of nonbonding electrons
Acids _____ proton H+
Donate
Bases _____ proton H+
receive
Seven strong acids !!!!
- nitric acid HNO3
- chloric acid HClO3
- perchloric acid HClO4
- sulfuric acid H2SO4
- HCl
- HBr
- HI
Strong bases!!!!
- 1A hydroxides: NaOH, KOH, etc…
- group II A hydroxides: Sr(OH)2, Ba(OH)2
Monoprotic acids
only has one proton per molecule to donate
ex: HCl -> H+ … Cl-
Polyprotic acids
can donate more than one proton per molecule
ex: H3PO4
Amphoteric substances
act as both acids and bases
“amph” = both
Ion-product constant for water: Kw
@25 C
Kw= 1.0 x 10^-14
What is auto-ionization of water
- water is amphoteric
-in pure H2O, a few molecules act as bases and same goes for acids
H2O + H2O = [H3O+] aq [OH-] aq
Relationship: pH - hydronium ion conc.
pH= -log[H3O+]
OR
10^ -(pH)
Relationship: pOH - hydroxide ion conc.
pOH= -log[OH-]
OR
10^ -(pOH)
[H3O+] -> pH
= -log[H3O+]
OR
10^ -(pH)
pH -> pOH
pH + pOH = 14 …
14 - pH = pOH
[OH-] -> pOH
= -log[OH-]
[H3O+] -> [OH-]
= Kw / [H3O+]
Relationship: magnitude of Ka to strength of acid
the greater the value of Ka, the stronger the acid
Relationship: magnitude of Kb to strength of base
acid-base conj. pairs
Keq= products / reactants
equilibrium expression
Keq= products / reactants
writing the eq. expression (exponents)
a A + b B <=> d D = e E
= [D]^d [E]^e / [A]^a [B]^b
what is K for a reverse rxn of:
2SO₃ <=> 2SO₂ + O₂
Kr= [SO₂]² [O₂]
I C E:
initial
change
equilibrium (I+C)
effect of volume/pressure change: (gaseous rxns only)
decrease: shift to side with fewer moles of gas
increase: shift to side with more moles of gas
effect of temp. change:
heat is reactant (endo):
increase… shift right
heat is product (exo):
increase … shift left
write conj. base for:
1. HBr
2. H2S
3. H2CO3
- Br-
- HS-
- HCO3-
write conj. acid for:
1. NO2-
2. NH3
3. OH-
- HNO2
- NH4
- H2O
which contain sets of acid-base conj. pairs?
1. HNO2 NO2-
2. H2CO3 CO3^2-
3. HCl ClO4-
4. HS- H2S
5. NH3 NH4+
1: acid, conj. base
4&5: base, conj. acid
To find Kc:
Kp/(RT) ^ delta n
To find Kp:
Kc(RT)^delta n
