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

Analyse the samples by titration and to decide which of the samples, if any have been watered down.

Extracts from this document...

Introduction

Titration Plan The Aim A trading standards officer suspects that a wholesaler is supplying fish and chip shops with vinegar that has been watered down. The officer has collected several samples of the vinegar from different shops, together with a sample of the same brand of vinegar direct from the manufacturer. My task in this assignment is to analyse the samples by titration and to decide which of the samples, if any have been watered down. I will then prepare a report for the officer showing the extent to which the vinegar samples have been watered down if at all. I was given the manufacturers sample and three other samples to test. The Variables The possible input variables are the concentration of the vinegar, the concentration of sodium hydroxide, the amount of vinegar, amount of sodium hydroxide, the amount of phenolphthalein (indicator) and the temperature. My possible outcome variables are the amount of vinegar needed to neutralize the sodium hydroxide and the speed of the reaction. The input variable I have decided to change is the concentration of the vinegar and the output variable I have decided to measure is the amount of vinegar needed to neutralize the sodium hydroxide. My control variables that I will keep the same to make my experiment fair are the amount and concentration of sodium hydroxide, the starting amount of vinegar, the amount of phenolphthalein and the same equipment. ...read more.

Middle

10. Stop when the indicator has changed the solution from purple to clear and note the reading on the burette. 11. Empty and rinse the conical flask and then refill and zero the burette. 12. Using the pipette filler, refill the pipette and let the solution out until the meniscus is on the line. 13. Repeat steps 5, 6 and 7. 14. Repeat step 8 but stop about 1cm before the previously recorded volume. Then add the vinegar drop by drop until the solution goes clear. 15. Record the volume added in a table. 16. Do at least three readings within 0.1 cm of each other for each sample. Scientific Knowledge Equation for the reaction: Acid + Alkali --> Salt + Water Sodium Hydroxide + Ethanoic Acid --> Sodium Ethanoate + Water NaOH + CH3COOH --> CH3COONa + H2O 1 Mole + 1 Mole --> 1 Mole + 1 Mole I know that it takes 1 mole of NaOH to neutralize 1 mole of CH3COOH and then you get 1 mole of CH3COONa and 1 mole of H20 amount of moles = concentration x volume a = cv = 0.1 x 25/1000 = 0.0025 moles of NaOH 0.0025 moles of sodium hydroxide and Ethanoic acid are needed each time. ...read more.

Conclusion

As the volume halves the concentration doubles, for example on my graph the volume is 26 cm and the concentration is 0.10 moles and when the volume is 13cm ,the concentration is 0.20 moles. On the second graph I plotted the axis was volume of vinegar against 1/concentration of vinegar. In this graph I have found that all the points join up to become a straight line. I have found that sample 1, 2 and 3 have been watered down because the concentration for those three samples is lower than the concentration of the manufacturers sample. Evaluation In my experiment I have completed it fairly, the equipment I used to make it fair was the same volume pipette and burette. This is because they have a line on them and the meniscus of the liquid is on the line so I will be using the same volume of liquid every time. On my first graph the first three points are joined up by more of a straight line than the curve that joins the 3rd and 4th points up. To make this more of a smooth curve I could have missed a point out of it to make it smooth. I have enough results to support my conclusion because every result I took was within 0.1 cm of each other. To further my experiment I could react all of the samples with magnesium and then the less concentrated vinegars will react slower. 1 Faye Cooke 10S ...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. Concentration of Vinegar

    It can also cause severe permanent eye damage. Pipette - always hold the pipette vertically close to the open end and not the tip. If broken, do not touch, use parker and brush to pack into the broken glass container.

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

    This was carried out four times, into 3 more wells. This was done so that an average of the titrations can be taken for the calculations. To each of these, 3 drops of bromothymol blue was added using the indicator pipette and stirred to mix the solution.

  1. Analysing the ethanoic acid concentration in different types of vinegars.

    x Volume)/1000 = (1 x 8.433)/1000 = 0.00843 Since one mole of acid reacts with 1 mole of NaOH the number of moles of acid is also 0.00843 moles per 50cm3 sample. Since 5 samples of acid were made from my original 50cm3 sample of vinegar.

  2. Determine the concentration or molarity of Ethanoic acid (CH3COOH) in two types of commercial ...

    To do this the process demonstrated in the plan has to be reversed, so: 0.9385 = to the no. mole in 1 dm3 (1000 cm3) and to be able to find out the percent mass data it is more convenient to know the no.

  1. Obtain pure samples of Ethanol (CH3CH2OH) and Ethanoic Acid (CH3COOH) from fermented Yeast (Saccharomyces ...

    which is made up of yeast, ethanol, water and glucose, using certain apparatus and techniques. In order to obtain the final result five stages/practicals will need to be carried out; . PRACTICAL 1 Preparation of Ethanol from glucose using yeast to carry out a fermentation in a bioreactor This will be carried out as a class demonstration.

  2. To see which antacid tablet is the most efficient out of 4 samples.

    All the above substances are alkaline and so, assuming that they must be around the same pH (they would be made the right pH so that the body could take the tablet), I can just add up how much of the alkali substances are there in each tablet and the

  1. Vinegar. In this investigation I am going to find out the concentration of ethanoic ...

    Instead of measuring the amount from a certain temperature, I will take the start temperature and then one at the end. The difference will then be taken. I will use a different measuring cylinder for each liquid, and the water will be taken from the tap.

  2. You are provided with a sample of vinegar which contains approximately 5g of ethanoic ...

    250cm� volumetric flask * Distilled water * Vinegar SAFETY CONSIDERATIONS: * Vinegar is a dilute aqueous solution of Acetic Acid. The pure acid is hazardous, yet when diluted it is not very dangerous. It has a very strong smell so use it in a ventilated environment.

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