Mnemonics for pH Titration Curves: Easy understanding and complete guide
pH Titration curves
Complete guide with mnemonics and comparison for titration curves of:
- Strong Acid vs Strong Base
- Weak Acid vs Strong Base
- Strong Acid vs Weak Base
- Weak Acid vs Weak Base
These combinations behave differently, and each titration curve has a distinct shape, equivalence point pH, and suitable indicators.
Quick Comparison Table:
| Titration Type | Starting pH | Buffer Region | Equivalence pH | Curve Shape | Suitable Indicator | Mnemonic Phrase |
| Strong Acid + Strong Base | Very low (~1) | ❌ No buffer | ~7 | S-shape, sharp rise | Phenolphthalein or Methyl orange | “Strong + Strong = Neutral Song” |
| Weak Acid + Strong Base | Moderate (~3–5) | ✅ Yes | >7 (~8.5) | Gradual rise, then sharp | Phenolphthalein | “Weak Acid + Strong = Basic Ending” |
| Strong Acid + Weak Base | Low (~1) | ✅ Yes | <7 (~5.5) | Dip, buffer, sharp rise | Methyl Orange | “Strong Acid + Weak = Acidic End” |
| Weak Acid + Weak Base | Moderate (~5) | ❌ Weak Buffer | ~7 or undefined | Flat & curved | ❌ No sharp indicator shift | “Weak + Weak = Weak Show” |
Mnemonics for Each Case:
Strong Acid + Strong Base
Mnemonic: “Strong + Strong = Neutral Song”
- Start pH: ~1 (acidic)
- Equivalence pH: ~7 (neutral)
- Sharp vertical rise at equivalence
- Indicator: Phenolphthalein or Methyl orange
Tip: Curve is steepest here — easiest to detect.
Weak Acid + Strong Base
Mnemonic: “Weak Acid + Strong = Basic Ending”
- Start pH: ~3–5
- Buffer region: Yes (half-neutralization point: pH = pKa)
- Equivalence pH: >7
- Indicator: Phenolphthalein (color change in basic range)
Tip: pH rises slowly at first due to buffer, then shoots up.
Strong Acid + Weak Base
Mnemonic: “Strong Acid + Weak = Acidic End”
- Start pH: ~1
- Buffer region: Yes
- Equivalence pH: <7
- Indicator: Methyl orange
Tip: Final solution is acidic; pH drops more gradually than strong–strong.
Weak Acid + Weak Base
Mnemonic: “Weak + Weak = Weak Show”
- Start pH: ~5
- No sharp jump, curve is gentle
- Equivalence pH: Varies — depends on strengths
- Indicator: ❌ No clear sharp region → use pH meter
Tip: No steep vertical section = no single suitable indicator
Visual Shape Descriptions:
| Case | Curve Shape |
| Strong acid + strong base | S-shape, sharp vertical at pH 7 |
| Weak acid + strong base | Gradual rise → sharp jump > pH 7 |
| Strong acid + weak base | Steep rise → equivalence < pH 7 |
| Weak acid + weak base | Flat, curved, no sharp equivalence |
