lecture 6/6 [ENDORSED]

[megangeorge-1K]

Hello
I was not able to attend lecture on Wednesday, 6/6. Does anyone possibly have the notes from that lecture?

Thank you!

[DomMaiorca_1I]

Oxides of Main Group Elements
- As discussed, metal oxides react with water to form strong bases.
- Many nonmetal oxides react with water to form acids.
Carbon Dioxide + Water <—> Carbonic Acid
CO2 (g) + H2O (l) <—> H2CO3 (aq)
Sulfur Dioxide = Water <—> Sulphurous Acid
SO2 (g) + H2O (l) <—> H2SO3 (aq)
- SO2 (g) comes from burning petroleum products, coal, etc.
- SO2 (g) reacts with water vapor to form acidic rain.
- Work through acid rain examples in textbook.
- Amphoteric Compound:
- Both basic and acidic character/properties.
- Between the metal oxides (bases) & nonmetal oxides (acids) there is a diagonal band of amphoteric oxides closely matching the diagonal band of metalloids.
- BeO, Al2O3, Ga2O3, SnO2, Sb2O3, PbO2
- Reaction between acid & base is neutralization, product is salt + water.
- Acid + Base <—> Salt + Water
- You don’t always get water, but you do always get salt. With a Bromstead acid & Bromstead base, you USUALLY get water.
- HCl (aq) + NaOH (aq) <—> NaCl (aq) + H2O (l)
- Acidic Solution : [H3O+]>[OH-]
- Basic Solution: [H3O+]<[OH-]
- More convenient to write [H3O+] & [OH-] as logarithms.
- Define concentration of H3O+ as: pH=-log10[H3O+]
- Log 1 = 0
- Log10 ^-14 = -14
- Most solutions have [H3O+] between 1 and 1.0x10^-14 mol.L-1
- pH scale: 0 (acidic) —> 14 (basic)
- [H3O+] of neutral water at 25degreesC is 1.0 x 10^-7 mol.L-1
- pH = -log[H3O+] = -log(1.0x10^-7) = -(-7) = 7
- Note: for a change in 1 pH unit, the [H3O+] changes 10x.
- Similarly, we define: pOH = -log[OH-] for reporting OH- concentration
- And for weak acid equilibrium constants: pKA = -log[KA] p = -log
Relative Acidity (properties that make an acid strong or weak)
1. Strong acids lose H+ easily
2. The resulting anion must be stable
3. Weaker (longer) A—H bond, easier to remove H+
EX: short, strong bond = less acidic // long, weaker bond = more acidic
HF < HCl < HBr < HI
H2O < H2S < H2Se < H2Te
4. Oxoacids more readily lose H+ if resulting anion is stabilized by electron withdrawing atoms which delocalize and stabilize the negative charge.
EX: (more acidic) Hypochlorous Acid (Cl—O—H) Hypobromous Acid (Br—O—H) Hypoiodous Acid (I—O—H) (less acidic)
- O—H bond has to be broken
- Lowest pKa is the strongest acid, highest pKa is the weakest acid
- Cl highest electronegativity, stabilizes negatively charge O by withdrawing e- density

[Chem_Mod]

Great Summary!

[megangeorge-1K]

thank you so much!
Very helpful!