# General Chemistry

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1. Convert between F and C (when C = 0, F = 32)
TF = 9/5TC + 32
2. Energy of electron jumping
• E relates to Z2/n2, where Z = nuclear charge
• E = constant (1/nf2 - 1/ni2)
• So, jump from higher initial ni = more E, farthest = most energy
3. Quantum numners
number of e in a level
• Number of e in an level = 2n2
• First QN = n = average radius, level
• Second QN = l = n-1---> 0
• Third quantum number = ml = +/1 all of l values
• 4ths = ms = spin
• L = shape, 0 = s, 1 = p, 2 = d, 3 = f
• ml = axis in shape, for l = 0, ml = 0 = sphere
• for l = 1, ml = -1, 0, 1 = 3 lobes for p
• Each lobe = 2 electrons
• So, s = 2, p = 6, d = 10
4. Z effective, periodic trends
• Zeff = nuclear pull = core e- + protons = 2 + protons so Z effective increases as go right, and decreases down
• EA, IE, EN all increase as you go right and up
5. Series for absorption
Photoelectric effect
• To n=2 = Balmer
• To n = 1 = Lyman
• To n = 3 Paschen
• hv (photon) = work + KE
• Remember charge and mass must match on each side
• Alpha decay = losing helium
• Beta decay = losing electron, so neutron converted to proton
• Positron decay = losing positive electron so proton converted to neutron
7. Equilibrium constant
Forward, reverse rate
Keq Change
Qrx
Volume
• Keq = P/R at eq
• forward rate = k1[R], reverse = k2[P]
• So, Keq = k1/k2
• Stoichimetric coeff = exponents
• Keq only changes with temperature, nothing else
• Qrx = P/R at any old time
• Be careful of volume with problems, doesn't always cancel in P/R
8. How to solve Keq problem
When to ignore +x and -x
• Always set up as + and -x, solve for Keq
• Note, adding up E components in gas proble
• Ignore x if,
• all reactants and Keq = <10-3
• R and P and K = 1
9. Complex equilibirum
LeChatleir's
• Happens if product of 1 rxn = reactant of second
• Multiple coeff of 1 rxn so numbers match, and do Keqn to get new Keq for the altered one
• Next to get whole Keq multiply this new Keq x other rxn's Keq
• LeChat; rxn goes back to eq if add or change something. Consider heat, endo exo, moles of gas etc
10. Molar solubility
Ksp
Common Ion Effect
• MS = true measure of solubility = max moles per volume
• Ksp = solubility product = [P1][P2]
• Solve like Ice box, +x, -x, but also, coeff = exponents
• x itself = molar solubility
• if question asks for moles dissolved after eq, do n times coeff, b/c x is in solubility/mole
• CIE = like reverse le chatlier's, can represent in ICE box
11. Arhenius Acid, B-L, Lewis
Neutral Water, 14
Ka
Kb
Conj pair
• Arhenius A = produces H3O in water
• B-L = proton doner
• Lewis A = lone pair acceptor
• Neutral at 25 C, pH = pOH, 7 = 7
• Ka, larger = higher P/R = better acid
• pka = -log Ka
• Kb, larger = better base
• pkb = -logKb
• For conjugate pair, pKa + pKb = 14
12. Strong, weak, very weak acids, bases
Typical strong acids, bases
Haloacid trend
Oxyacid anatomy
• Strong, K>1, pka<0
• Weak, 10-14<K<1, 0<pka<14
• Veryweak, K < 10-14, pka > 14
• Same trend for bases, except, Kb and pKb
• Strong acids = oxacids and haloacids
• Strong bases = carbides (Li-Butyl), amides (Li Dia, NR2), alkoxides, hydrides, hydroxides
• Haloacids, opp of FONClBrISH, I>Br>Cl>F
• Oxyacid, more O, more EN central atom = more acidic
• C.A.Ph.AlcAlpha, 5,10.15.20
13. Logarithms
Equation for pH when you know pKa and HA
Equation for pOH when you know pKb and A-
• log (axb) = loga + logb
• log (a/b) = loga - logb
• log 2 = .3
• log 3 = .48
• pH = 1/2pKa - 1/2log[HA]
• pOH = 1/2pKb - 1/2log[A-]
• note, HA or A must be > Ka or Kb
• and pK must be 2<pK<12
14. pH and pka
Amino acids
HH equation
• if pH < pKa, protonated, conj acid presides
• if pH > pKa, deprotonated, conj base presides
• AA, C.A., pka = 2-3, so deprot, NH3, pka = 9-10, prot
• if conj a and conjb present
• pH = pKa + log([A]/[HA])
15. Buffer range
Recipe for buffer
• Buffer range when A- = HA of conjugate pair
• But also, range in pH = + and -1 from pKa
• Since HH says pH = pKa + log([A]/[HA]), then that means between when A-/HA = 10/1---1/10
• Recipe; 1/2 HA + 1/2A of conj pairs OR
• 1/2 A + 1SA OR 1/2 HA + 1 SB
• SA and SB will react completely, should be unrelated to original acid or base
• Pick HA or A with pka etc near pH you want
16. Titrations, SA + SB
pH before titration
pH before eq point
pH at eq point
pH after eq point
• SA + SB, equivalence = when equal moles added = pH 7 aways.
• SA into WB or SB into WA
• if second, when 1/2 equivalent added = buffer, at 1 equivalent, pH > 7 because produce all conjugate base
• opposite for SA into WB
• To find pH of weak acid before titration = 1/2pKa - 1/2log[HA]
• Before eq point, near buffer zone, use HH. At exactly 1/2 eq point, pH = pKa
• At eq point, pH = 1/2(pka + pH titrant)
• After eq point, pH = 14 - pOH, pOH = -log(molarity of SB * each new ml added/total liquid added so far)
17. Indicators
• Indicators, H-IND -> H+ + IND-
• Treat like HA and A of buffer
• Color changes at eq point
• pH solution = pKaind +log[Ind/Hind]
• Choose pkA indicator that is + or -1 from equivalence point of acid and base titrating
18. Best ideal gas
van der waals gas law
• Best ideal gas = decrease collisions= low P, increase temp so IMF overcome
• (P+an2/V2)(V-nb)=nRT, so Pressure usually less or more depending on repel or attract, and V is usually less
• Usually real gas behaves in a way to fall short of any predictions of Ideal Gas Law
Boyle's Law
Charle's Law
Partial pressure
liquid pressure
• V/n = V/n
• PV=PV
• V/T = V/T
• PP = mole fraction x total pressure
• LP, difference in heights = density x gravity x change h
• absolute = Patm + pgh
20. Gas speed, kinetic energy, trends
root mean squared speed
Diffusion, effusion, iffusion
Isotropic enrichment
• 1/2mv2 = 3/2RT
• Use R as 8.3 if includes speed
• v2/v1 = aqrt(m1/m2) = sqrt(T2/T1)
• rms speed = sqrt (3RT/m)
• lighest gas diffuses fastest
• effusion, gas withmore conc, lighest = fastest
• Can separate isotopes based on weight, lightest effuses first
21. o
 Author: Anonymous ID: 140772 Card Set: General Chemistry Updated: 2012-03-12 02:58:21 Tags: Gen Chem equations Folders: Description: equations Show Answers: