Kjeldahl method (nitrogen estimation) (%N = (1.4 × Normality of acid × Volume of acid neutralized by NH₃) / mass of organic)
jee-mainjee-advancedneet-ug
%N = (1.4 × Normality of acid × Volume of acid neutralized by NH₃) / mass of organic compound
What each symbol means
| Symbol | What it stands for |
|---|---|
| W | Mass of organic compound taken (g) |
| 1.4 | Derived from 14 (atomic mass of N) × 100 / 1000 — converts milliequivalents to percentage |
| N_acid | Normality of the standard acid (H₂SO₄) |
| V_acid | Volume of acid (mL) consumed by evolved NH₃ |
When to use this
Does NOT work for compounds where N is in a ring (pyridine, quinoline), nitro groups (–NO₂), azo groups (–N=N–), hydrazine, or N bonded to N/O. These groups don't fully convert to (NH₄)₂SO₄ during digestion.