• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Back Titration - Percentage Fertilizer

Extracts from this document...


Back-Titration: Percentage by Mass of Nitrogen in a Fertiliser Procedure: * Fertiliser is carefully weighed and put into a conical flask. * Aqueous sodium hydroxide is then pipetted into the conical flask and gently boiled over a busen burner. * When the vapour no-longer smells, a burette is filled with Hydrochloric acid and some bromothymol blue (indicator) * There are 3 attempts. * Sodium Hydroxide is pipetted. * The indicator is once-more used. * Titration can now begin. * We stop titrating once the liquid turns green/yellow. * The results of 3 attempts are noted. DCP: NaOH added to Fertiliser = 25mL � 1mL � 4%. Weight of Fertiliser g. ...read more.


NH3 Formula of the reaction: NH4X + NaOH ? NaX + NH3 + H2O. Other possibilities with a non-mono-atomic X would face the same problem, being that the ratio of moles of Nitrogen to those of Sodium Hydroxide will still be maintained at 1:1. Moles of NaOH un-used in initial reaction = cv = 1.75*0.01 = 0.0175 moles. Moles in total to start with = cv = 1.75*0.025 = 0.0438 moles. Used moles = 0.0438 - 0.0175 = 0.026 moles. Mass = moles*mass of 1 mole = 0.026*14 = 0.364g. Percentage by mass of Nitrogen in the Fertiliser = (0.364/2.085)*100 = 17.5% Error = 1.6% + 2.4% + 0.6% + 4% = 8.6% ? ...read more.


By simply making sure that the weight was 2.00g. each time, we could have largely simplified the process and made it a lot more accurate. We made sure in all cases that the NH4 was no-longer present in the boiling solution by holding wet PH paper over it or carefully smelling it. But by the end of the procedure, it is very simple to attempt to make the process faster and then forget to ensure that the NH4 is entirely used up. The PH paper helped to make it more accurate, because it would have been exceedingly difficult for us to make sure that all the NH4 had reacted simply by smell. In either case, we can't be 100% sure that it all reacted with the Sodium Hydroxide, which would have later changed our titration results. 25/09/2009 Back Titration of Nitrogen in a Fertiliser 2 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Chemistry essays

  1. Analysis of the Nitrogen Content of Lawn Fertiliser

    Sodium hydroxide can react with the proteins in the eye. * Wear a lab coat. Hydrochloric acid can cause severe skin irritation. If any is spilt on the skin, wash it off with water immediately. * Ammonia vapour irritates the skin, eyes, and respiratory system.

  2. IB questions and answers on Atomic Theory

    from n = 4 to n = 1 b) from n = 4 to n = 3 c) from n = 2 to n = 1 d) from n = 1 to n = 4 33. Consider only the first four primary energy levels of a hydrogen atom. The transition that would result in photon of the longest wavelength would be a)

  1. alkali titration

    c = n/v c = 0.097mol dm-3 �0.001 = 0.097mols � (0.001/0.097 x 100%) = 0.097mols dm-3 �1.03% v = 20.0cm3 �0.04 = (20.0/1000) � (0.04/20.0 x 100%) = 0.020dm3 �0.2% n = ? n = c x v n = 0.097 �1.03% x 0.020 �0.2% n = 0.00194 � (1.03 + 0.2)% ?

  2. FInding the percentage purity of CACO3 in egg shell

    4.931g Pipette solution (±0.060cm3) 25.00 cm3 Burette solution (±0.020cm3) 50.00 cm3 Volumetric flask (±0.120cm3) 250.0cm3 Table shows the chemicals that were used and there respective volumes Chemicals used Volume of chemicals used CaCO3 solution (±0.12 cm3)

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work