To determine the amount of ammonia in a sample of household cleaning product, 'cloudy ammonia', in the form of NH4OH through the process of volumetric analysis.

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Volumetric Analysis of Ammonia in Household Cleaning Product

Aim:

To determine the amount of ammonia in a sample of household cleaning product, ‘cloudy ammonia’, in the form of NH4OH through the process of volumetric analysis.

Introduction:

Neutralisation refers to the process whereby an acid reacts with a base in stoichiometric proportions to each other to form a salt and water. In this experiment, the neutralisation reaction can be summarized by the following equation:

HCl (aq) + NH4OH (aq)           NH4Cl (aq) + H2O (l)

In this prac, the primary standard is Na2CO3. Primary standards are substances that possess certain properties (i.e. it is soluble), which enable it to be made up into a solution of a known concentration with distilled water to high degree of accuracy. A secondary standard on the other hand, is any solution that has an accurately known concentration. In this experiment, HCl acid is the secondary standard. The standardising of HCl can be summarized by the following equation:

2HCl (aq) + Na2CO3 (aq)            2NaCl(aq) + CO2 (g) + H2O (l)

Since sodium carbonate is deliquescent, it is kept in a desiccator to prevent it from absorbing water vapour from the atmosphere. The equivalence point of a titration is the point where the reactants are present in stoichiometric proportions to each other. The end point of a titration is the stage at which the chosen indicator (methyl orange) changes colour to show that a reaction e.g. neutralisation has occurred. In theory, the equivalence point should equal the end point.

Materials:

  • 1x 10ml Pipette
  • 1x 20ml Pipette
  • 1x Burette
  • 2x 250ml Volumetric flask and stopper
  • 3x Conical/Titration flask
  • Sodium Carbonate (Na2CO3)
  • 1x Electronic balance
  • Distilled water
  • Hydrochloric Acid
  • Methyl orange indicator
  • 1x Clamp and stand
  • 10ml of cloudy ammonia
  • 1x Glass dropper
  • 1x 50ml beaker
  • 1x Glass funnel
  • 1x Plastic bottle and lid
  • 1x Spatula
  • 1x white tile

Procedure:

Part 1: Preparation of Na2CO3 Solution:

  1. The mass of the Na2CO3 required to prepare a 250ml solution of approximately 0.05M was calculated and recorded.
  2. An empty beaker was weighed and the mass recorded in Table 1.1.
  3. The beaker was kept on the balance and the Na2CO3 added to the beaker until the required amount (as calculated in step 1) was reached. The mass of the beaker and Na2CO3 was recorded in Table 1.1.
  4. The Na2CO3 was transferred into the volumetric flask. The ‘empty’ beaker was then weighed again to ensure that all the Na2CO3 had been transferred.
  5. Some distilled water was added to the volumetric flask to dissolve the Na2CO3.
  6. Once the Na2CO3 had dissolved, distilled water was added to the flask until the bottom of the meniscus reached the 250ml mark on the flask.
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Part 2: Standardisation of HCl:

  1. The correct rinsing procedures were used to rinse out all the glassware. (See Table 4.1).
  2. 50ml of HCl acid was poured into the burette.
  3. 20ml of the Na2CO3 solution from part 1 was then transferred into a conical flask using a pipette.
  4. 2-3 drops of methyl orange indicator was added to the Na2CO3 solution.
  5. The HCl acid was titrated until the indicator change from yellow to ‘salmon pink’ (end point). The volume of HCl used was then recorded in Table 2.2.
  6. Steps 3-5 were repeated until two or three ...

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A five star piece of work. Excellent introduction shows a clear understanding of titration and shows good balanced equations. The procedures are excellent and the results show accuracy and lots of skill. Excellent calculations used and analysis of results.