CHEMCA
EXAM MASTER FORMULA SHEET
Titration & Volumetric Analysis
Essential for JEE Main, Advanced & NEET Quant Analysis
1. Fundamental Volumetric Laws
The Law of Equivalence:
\[ N_1 V_1 = N_2 V_2 \]
Equivalents of Acid = Equivalents of Base (at neutralization point)
Molarity-Normality Relation:
\[ N = M \times n\text{-factor} \]
Number of Equivalents:
\[ \text{Eq} = \frac{W}{E} = N \times V(L) \]
2. Indicators & pH Range
| Type of Titration | pH at Eq. Pt | Suitable Indicator |
|---|---|---|
| SA vs SB | 7 | Any (PhPh, MeOH) |
| WA vs SB | > 7 | Phenolphthalein |
| SA vs WB | < 7 | Methyl Orange |
| WA vs WB | \(\approx\) 7 | No suitable indicator |
Indicator Theory (Ostwald's):
\[ pH = pK_{In} + \log \frac{[In^-]}{[HIn]} \]
Color transition occurs usually within range: \( pK_{In} \pm 1 \)
3. Double Titration (JEE Advanced Special)
Reaction of mixtures like \(NaOH + Na_2CO_3\) or \(Na_2CO_3 + NaHCO_3\) against HCl.
Phenolphthalein End Point (\(V_P\))
- • \(NaOH \longrightarrow\) 100% neutralized
- • \(Na_2CO_3 \longrightarrow\) 50% neutralized (to \(NaHCO_3\))
- Eq: \( n_{NaOH} + \frac{1}{2}n_{Na_2CO_3} = n_{HCl} \)
Methyl Orange End Point (\(V_M\))
- • \(NaOH \longrightarrow\) 100% neutralized
- • \(Na_2CO_3 \longrightarrow\) 100% neutralized (to \(CO_2\))
- • \(NaHCO_3 \longrightarrow\) 100% neutralized
- Eq: Total alkalinity neutralized
Case: \(Na_2CO_3 + NaHCO_3\) mixture: \( n_{Na_2CO_3} = 2 \times V_P \text{ and } n_{NaHCO_3} = V_M - 2V_P \)
4. Back Titration & Specific Methods
Back Titration Logic:
Useful for insoluble or slow reacting solids.
\[ \text{Eq. of Substance} = \text{Total Eq. of excess reagent added} - \text{Eq. used in back titration} \]
Kjeldahl's Method (\% N):
\[ \%N = \frac{1.4 \times N \times V}{W} \]
\(V\) = vol of acid used by \(NH_3\)
Hardness of Water:
\[ \text{Hardness (ppm)} = \frac{\text{Eq. of } CaCO_3 \times 10^6}{\text{Mass of water}} \]
5. Permanganometry Essentials
Self-Indicator: \(KMnO_4\)
Reaction in Acidic Medium (\(H_2SO_4\)):
\[ MnO_4^- + 8H^+ + 5e^- \longrightarrow Mn^{2+} + 4H_2O \]
n-factor = 5
Warning: \(HCl\) cannot be used in \(KMnO_4\) titrations because \(KMnO_4\) oxidizes \(Cl^-\) to \(Cl_2\). Use \(H_2SO_4\).
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