Easy Practice — Set 2

Quick Recap — Qualitative & Quantitative Analysis

• Sodium fusion (Lassaigne's): N $\to$ Prussian blue; S $\to$ violet (nitroprusside) / black ($PbS$); N+S $\to$ blood-red (thiocyanate); halogen $\to$ AgX (white $Cl$, pale-yellow $Br$, yellow $I$).
• Quantitative: C & H by combustion (Liebig, weigh $CO_2$ and $H_2O$); N by Dumas (volume of $N_2$) or Kjeldahl (titrate $NH_3$); halogens/S/P by Carius (as AgX / $BaSO_4$ / $Mg_2P_2O_7$).
• % element from the mass of the derived compound; then empirical $\to$ molecular formula.
• Kjeldahl is not suitable for N in rings or $-NO_2$/$-N=N-$ compounds.