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

To determine the concentration of acetic acid in an unknown sample of vinegar by titrating a known volume ofthe acid solution against a standardized basic solution.

Extracts from this document...

Introduction

S.6A Karen Kwok (8) VA2 22th, September, 2002. Chemistry Laboratory Report Title: Acid-base Titration Date: 20th, September, 2002. Objective: (1) To determine the concentration of acetic acid in an unknown sample of vinegar by titrating a known volume of the acid solution against a standardized basic solution. Procedures: Part A: Standardization of 0.1M sodium hydroxide solution using potassium hydrogen phthalate as the primary standard. 1. 5.010g of analytical grade potassium hydrogen phthalate was weighted and dissolved in deionized water in a beaker. 2. After all the KHC8H4O4 was dissolved, the solution was then transfer to a 250 cm3 volumetric flask. 3. Then the volumetric flask was filled to the graduation mark with deionized water. 4. The volumetric flask was stopped. The flask was turned upside down in order to mix the solution well. 5. 25 cm3 of KHC8H4O4 solution from the volumetric flask was transfered in a conical flask using a pipette and pipette filler. 6. ...read more.

Middle

Therefore the average volume of 0.0500 M sodium carbonate required for neutralization: = 25.55 + 25.30 +25.50 3 cm3 =25.45 cm3 No. of moles of 250 cm3 KHC8H4O4 in volumetric flask = Mass Molar Mass = 5.010 204.23 mol =0.025 mol No of mole of 25 cm3 of KHC8H4O4 =0.025 � 25 250 =0.0025mol According to the equation, 1 mole of NaOH required 1 mole of KHC8H4O4 for complete neutralization. ?No of moles of NaOH= 0.0025mol Molarity of NaOH solution = No. of moles of NaOH Volume of solution = 0.0025mol 0.02545dm3 =0.098M The volumes of 0.098M NaOH solution required for neutralization are: 24.50 cm3, 22.65 cm3. Therefore the average volume of 0.098M sodium hydroxide required for neutralization: = 24.50 + 22.65 2 cm3 = 23.58 cm3 NaOH (aq) + CH3COOH(aq)?CH3COONa (aq) + H2O(l) 0.098M ?M 23.58 cm3 25 cm3 No. of moles of NaOH in 23.58 cm3 = Molarity of solution �Volume of solution = 0.098 mol dm3 �0.02358 dm3 = 0.0023mol According to the equation, 1 mole of NaOH required 1 mole of CH3COOH for complete neutralization. ...read more.

Conclusion

Potassium hydrogen phthalate can be act as a primary standard to standardize NaOH. It is because it is a monoprotic acid whose formula is KHC8H4O4 and has a high molecular weight (204.22 g/mol). Also, the exact mass can be easily determi ned by weighing the dried acid on an analytical balance. It is stable and not hydroscopic, and it fits all the propeties of a primary standard. 3. Is methyl orange a suitable indicator in this experiment? Why? Ans: Methyl orange is not a suitable indicator in this experiment. Because for strong base (NaOH) with weak acid (KHC8H4O4), the pH at the equivalence point is always greater than 7 because of the conjugate base is basic. And from the titration curve for strong acid with weak base, we know that pH at the equivalence point is approximately 8.8, and the dramatic change in pH cannot cover the pH range of methyl orange which is (3.1-4.4). But it can cover the pH range of phenolpthalein (8.3-10.0), therefore it is more suitable for us to use phenolpthalein in this experiment. Titration for weak acid with strong base ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous 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 GCSE Aqueous Chemistry essays

  1. identifying an unknown compound

    the flow chart will be drawn separately from the test, because drawing a flowchart that includes,, tests, observation and inferences will be too rough. Reagents and Apparatus Bromine Water Test tubes/Test tube racks Acidified Potassium Dichromate (VI) (K2Cr2O7) 2,4-Dinitrophenylhydrazine (2,4-DNP)

  2. Titrating Sodium hydroxide with an unknown molarity, against hydrochloric acid to find its' molarity.

    * Methyl Orange indicator * Spatula * Weighing bottle * Glass rod * Top pan balance excellent _2b In this experiment we will be using 0.10M sulphuric acid and 0.10M sodium carbonate solution, which are dangerous chemicals. Sodium carbonate, irritant, wear eye protection/protective gloves when weighing solid1 Sulphuric acid, very

  1. In order to find out the exact concentration of sulphuric acid, I will have ...

    Make sure all equipment is cleaned thoroughly prior to the start of the titration. Whilst transferring sodium carbonate solid to the beaker, all visible particles are transferred and none are left behind. This will allow exactly 2.65g of sodium carbonate to be conveyed precisely.

  2. Finding out how much acid there is in a solution.

    This shows that my results are reliable even though they are not precise. Even though my results are accurate they are not perfect. There is always some sort of error that affects an experiment. This is called human error.

  1. Investigation to Determine the Composition of Commercial Vinegar.

    Stirring Rod Funnel Preliminary Experiment Preliminary Experiment (choosing indicators): We have been given two Indicators to try, they are Screened Methyl Orange which changes colour at pH 3.7 and Phenolphthalein which changes colour at pH 8.4. I have to plan an experiment to find out which is the best indicator to use in the titration experiment.

  2. Back Titration to find the Concentration of Vinegar (Ethanoic Acid)

    known concentration and sodium hydroxide of an unknown concentration, there was no direct possible way to find the concentration of the ethanoic acid. This lead to carrying out two separate titrations, which is called a back-titration, as we must find the concentration of the sodium hydroxide to then find the concentration of the ethanoic acid.

  1. Titration with a primary standard.

    touch it to the side of the Erlenmeyer flask to draw off the last drop. In the process of delivering the exact volume of liquid to the flask using this kind of pipet, some pipets are designed to have the last amount of liquid blown out or even washed out,

  2. Identification of an unknown organic compound

    with 2-3cm3 of water. Add a drop of phenolphthalein and shake the test tube. Add sodium hydroxide till there's a change in color. Heat in a water bath and if the test is positive the substance will go clear again.

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