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

Analysis of the Nitrogen Content of Lawn Fertiliser

Extracts from this document...

Introduction

CHEMISTRY INVESTIGATION Analysis of the Nitrogen Content of Lawn Fertiliser Research Question: What is the percentage by mass of nitrogen (from the ammonium ion NH4+) in Bunnings Green Up brand of lawn fertilizer compared to the manufacturer's specification of 12.3%? Aim: To determine the percentage by mass of available nitrogen, present as the ammonium ion, in Bunnings Green Up brand of lawn fertiliser, then comparing it with the one specified by the manufacturer. Hypothesis: Since the ammonium ion (NH4+) present in fertilisers is a weak acid, it is hard to obtain an exact end point. Hence, back titration can be used to determine the percentage by mass composition of nitrogen in the fertiliser. To deduce the amount of nitrogen in ammonia, the NH4+ ion is reacted with an excess of NaOH, and the amount of unreacted NaOH found by titration with HCl is used to deduce the amount of NH4+ ion present by subtracting it from the initial amount of NaOH to find the amount that reacted with it. From this, the percentage by mass of nitrogen present in the fertiliser can be found and subsequently compared to the manufacturer's specification. It is hypothesized that the percentage by mass of nitrogen present in the fertiliser will be similar or close to that specified by the manufacturer (12.3%). ...read more.

Middle

reacted = 9.58 � 10-4 mol 4. The mole of ammonium in 20 cm3 aliquot and 250 cm3 using the reaction between ammonium and sodium hydroxide: NH4+(aq) + OH-(aq) --> NH3(g) + H2O(l) Molar ratio for NH4+ to NaOH is 1:1 Therefore, the mol of ammonium would be equal to that of sodium hydroxide: n(NH4+) in 20 cm3 = 9.58 � 10-4 mol n(NH4+) in 250 cm3 = 9.58 � 10-4 � n(NH4+) in 250 ml = 0.011975 mol 5. Find the nitrogen content by mass in ammonium ion (NH4+). Molar ratio for NH4+ to N is 1:1 Therefore, n (N) = 0.011975 mol m(N) in NH4+ = n � Mr (g) of N in NH4+ = 0.011975 � 14 m(N) in NH4+= 0.16765 g 6. The percentage by mass of nitrogen found in fertiliser: % by mass of N = m(N) in the Sample x 100 Sample mass % by mass of N = � 100% % by mass of N = 13.87% � 1.00% found in the sample Bunnings Green Up fertiliser The difference between the theoretical value (manufacturer's specification) and the experimentally found value: 13.87% - 12.3% = 1.57% The percentage uncertainty: � 100 = 7.21% The percentage difference: � 100 = 12.76% Since the % difference is greater than the % uncertainty, it is suggested that systematic errors are present in this investigation. ...read more.

Conclusion

This may be overcome by using another indicator that allows for a clearer colour contrast. Another possible limitation which may have impacted the results is that some ammonia may still have been present in the conical flask. Although the red litmus paper may have served its purpose, this may still occur as a result of not boiling the solution long enough and thus some ammonia may not have evaporated. The result of this is that the ammonia in the solution will react with the hydrochloric acid, and therefore more hydrochloric acid will be required for the equivalence point to be reached, affecting the titre volume. This can be easily overcome by ensuring that the fertiliser solution containing water and sodium hydroxide is boiled for long enough so that all ammonia can evaporate, while simultaneously ensuring that the solution remains at a constant 90mL. The use of tap water may also have affected the results. It may not have been at a pH of 7 or may contain other contaminants such as salts which may ultimately interfere with the results. To overcome this, the most effective way is to use deionised water. Conclusion: It was found that the percentage by mass of nitrogen from the ammonium ion in Bunnings Green Up brand of lawn fertilizer was 13.9% (? 1.00%). This was very close to the percentage of nitrogen in lawn fertiliser as specified by the manufacturer ? 12.3%. ...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. IB chemistry revision notes

    * Tends to be faster in gases, slower in liquids and very slow in solids. Kinetic Theory * Pressure --> The measure of the number and speed of the molecules hitting the walls of the container per second. o If the molecules hit the container walls more often then o

  2. Enthalpy Change Design Lab (6/6)How does changing the initial temperature (19C, 25C, 35C, and ...

    This will ensure that the molar enthalpies will be exclusively concerning the neutralization of aqueous hydrochloric acid, and aqueous sodium hydroxide. 2. The concentration of both solutions of KOH(aq) and HCl(aq) must be held constant, and in extension, the number of moles of KOH(aq)

  1. Aim. To find the identity of X(OH)2 (a group II metal hydroxide) by determining ...

    If the concentration was not to be same throughout, then this will cause different ratios of the components of the solution that might cause different volume of HCl to be obtained for the neutralization to occur. 4. Same volume of X(OH)2 This will be controlled by using the same batch of X(OH)2 and from the same source i.e.

  2. Free essay

    Energy content Cal/g

    Final Mass of food (+/- .005g) Time ( Seconds) Temperature (+/- .5 �C) Water (+/- .5ml) One 0.81 0.26 0 24 50 15 24 30 25 45 26 60 28 75 29 Two 0.81 0.25 0 23 50 15 23 30 24 45 24 60 25 75 26 Three 0.82

  1. Acids/Bases Design Lab. How does a change in the pH value of a solution ...

    will be discussed at further length in the appendix section of this investigation. This means that at precisely one minute, the hydrochloric acid solution must be emptied from the beaker containing the reaction between it, and the zinc metal strip, and rinsed with distilled water.

  2. pKa. When constant successive portions of Sodium Hydroxide are added to Acetic Acid; how ...

    mixed with acid. In other words, the volume of NaOH dropped into the acid is controlled but what is changed is the amount of base in the conical flask. (1 cm3 will always be followed with 1 cm3, there will be no change in how much you put in each

  1. Measuring the fatty acid percentage of the reused sunflower oil after numerous times of ...

    Dependent Variable: Fatty acid percentage of the sunflower oil. Constant Variables: Time, temperature, amount of oil, pressure, brand of oil, concentration of the solutions (phenolphthalein and KOH), amount of the indicator, amount of the alcohol for each sample, amount of oil samples.

  2. The use of volumetric flask, burette and pipette in determining the concentration of NaOH ...

    1.0 2.0 2.0 2.0 Final Reading (mL) 27.86 28.68 28.86 28.74 Volume of NaOH used (mL) 26.86 26.68 26.86 26.74 Average volume of NaOH used: 26.86 + 26.68 + 26.86 + 26.74 = 26.79mL 4 ________________ Discussion An acid-base titration is when you add a base to an acid until the equivalence point is reached which is where the moles of acid equal the moles of base.

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