Analysis of N Total by distillation

Principle Analysis
Urea in destruction with sulfuric acid to form ammonium sulfate and releases CO2, NH3 of Ammonium Sulfate then distilled {(NH4) 2SO4 when added NaOH and heated to release NH3} and distilled accommodated with H2SO4. Excess acid the titration back with standard NaOH solution.

Reaction

2 (NH2) 2CO + 2H2SO4 hydrolysis / (NH4) 2SO4 + CO2 + H2O

(NH4) 2SO4 + 2NaOH (excess) (distilled) / 2NH3 + Na2SO4 + 2H2O

2NH3 + H2SO4 excess (purple) mix / (NH4) 2SO4
2NaOH excess H2SO4 + Na2SO4 + 2H2O

Reagents and equipment
Reagent

    Concentrated sulfuric acid

    NaOH 40%.

    Indicators PP 1% in Alcohol

    Mix indicator

    Standard solution of 0.25 N NaOH

    Standard solution of H2SO4 0.5 N.
Tool

    1 (one) unit Vapodest.

    Nessler tube

    Volume Pipette 10 ml

    Erlenmeyer

    Electric stove

    25 mL burette.

    Stirrer.

Work Procedures
- Example weighed 0.5 g, was added Nessler tube and add a little distilled water
- Then added 10 mL of concentrated sulfuric acid and didestruksi on the stove.

- After the destruction of the finished cooled with a fan, PP indicator add Nessler tube.

- Before performing distillation by means vapodest sure faucet flowing cooling water, Nessler  tube inserted in vaodest tool, also previously erlenmeyer containing 25 mL of 0.5 N H2SO4 and indicators Mix.
- The tool is positioned to show "exchecution method". Then reagent button pressed until the solution turned into a Nessler tube pink.
- The middle button is pressed three times until the distillation run. Distillation wait until completion (5 minutes).
- After completion erlenmeyer distillate taken and excess H2SO4 the titration with NaOH 0.5 N.