8 Core Mnemonics for OC-11

Mnemonic 1: HDPE vs LDPE "HDPE: Zigzag Neat (ZN = Ziegler-Natta) — straight chains, High Density." "LDPE: Lots of Pressure (LP) → Loose/branched chains, Low Density." Key contrast: H = ZN catalyst + Low pressure. L = No special catalyst + High pressure.

Mnemonic 2: Nylon numbering "6,6 = Two sixes = Two monomers. Just 6 = One monomer (Caprolactam)." "One comma → two monomers. No comma → one monomer." (Nylon-6 vs Nylon-6,6)

Mnemonic 3: Heavy metal disease pairs "Hg → Mi (Mercury-Minamata — both start with 'M'). Cd → It-ai (Cadmium — Cd sounds like 'Cadmium Destroys' bones)." Full: Mercury = M disease (Minamata). Cadmium = I disease (Itai-Itai). Lead = Neurological (LeadN).

Mnemonic 4: Acid rain pH "5.6 = CO2 dissolved (natural). Below 5.6 = Acid rain (artificial). NOT pH 7." Remember: "Rain has CO2, so it's always 5.6 naturally."

Mnemonic 5: Smog types "London = COLD + SO2 + REDUCING = Like Old London fog (cold, sulfurous)." "Photo = WARM + OZONE + PAN + OXIDIZING = Like LA sunshine making ozone." Keyword contrast: London → Reducing → SO2. Photo → Oxidizing → O3 + PAN.

Mnemonic 6: CFC → Ozone destruction "Cl• is the KILLER that NEVER DIES. One Cl• kills 100,000 O3 because it regenerates." Steps: CFC → UV → Cl•; Cl• eats O3 → ClO•; ClO• + O → Cl• (reborn). Cycle repeats 100,000 times.

Mnemonic 7: BOD scale "Five and Below = Clean Fellow. Seventeen and Above = Dirty Sewage." BOD < 5 ppm = clean water. BOD > 17 ppm = heavily polluted/sewage.

Mnemonic 8: Polymer linkage types "AMINE + ACID = AMIDE (Nylon). ALCOHOL + ACID = ESTER (Dacron). PHenol + HCHO = PH enoset (Bakelite)." Or: A + A = Amide. A + OH = Ester. Ph + H = Hard thermoset.