Titration Essays

Titration Essays Titration Essay Titration Essay 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 VariablesThe 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.PredictionMy prediction is The higher the concentration of vinegar the less vinegar needed to neutralize the solution of vinegar and sodium hydroxide because if the vinegar has a low concentration then it contains a smaller number of moles per litre. So therefore more of the vinegar would be needed to neutralize the sodium hydroxide. If the vinegar was of a higher concentration less of it would be needed to neutralize the sodium hydroxide.Equipment ListBurettePipettePipette fillerConical flaskBeakers x2FunnelClamp standWhite tilePhenolphthalein indicatorSodium hydroxideVinegar samples: manufacture rs, sample 1,2,3Diagram of EquipmentRisk AssessmentI decided to make the experiment safe by wearing goggles at all times and not sitting down while doing the experiment. Also I tried not to spill and liquid or get any on my clothes and skin.Step by Step ProcedureThis is what I did:1. I will get all equipment out that is on the equipment list.2. I will label and fill two beakers with the reacting solutions.3. I will pour a little of the vinegar into the burette to rinse it. Then pour away the solution.4. I will fill the burette with vinegar and then let the solution out until the meniscus is on the zero line.5. Then using a pipette filler I will rinse out the pipette using the sodium hydroxide and then pour it away. Then fill the pipette to way past the line.6. Carefully let the solution out until the meniscus is on the line.7. I will then run the solution into a conical flask.8. I will add 7 drops of indicator and the solution will turn purple and put it on the white tile that is on the clamp stand.9. Run the solution from the burette into the conical flask a bit at a time, swirling the flask all the time.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 KnowledgeEquation for the reaction:Acid + Alkali Salt + WaterSodium Hydroxide + Ethanoic Acid Sodium Ethanoate + WaterNaOH + CH3COOH CH3COONa + H2O1 Mole + 1 Mole 1 Mole + 1 MoleI 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 H20amount of moles = concentration x volumea = cv= 0.1 x 25/1000= 0.0025 moles of NaOH0.0025 moles of sodium hydroxide and Ethanoic acid are needed each time.The less concentrated the vinegar the smaller the number of moles it will contain per litre so it will therefore take more of the solution to neutralize the solution.Test RunsRun12345Amount of acid needed (cm )272727.126.727.1My test runs were to show me how the equipment was set up and how the experiment worked and what I had to do in the experiment.Recording ResultsI recorded my results in a table but also in a graph. I will take an average of each set of results.SampleRun 1- Amount of vinegar needed (cm )Run 2- Amount of vinegar needed (cm )Run 3- Amount of vinegar needed (cm )Average amount of vinegar needed (cm )Manufacturers sample7.908.007.907.93Sample 116.5016.5016.6016.53Sample 225.9026.0025.9025.93Sample 334.5034.5034.6034.53The reaction that takes place is the neutralization of sodium hydroxide and eth anoic acid.Acid + Alkali = Salt + WaterCH3COOH + NaOH = CH3COONa + H2O1 mole + 1 mole = 1 mole + 1 moleConclusionHere are my calculations to find out the concentration and 1/concentration of each of the samples of vinegar. The calculation is: concentration = amount in moles/volume x 1000.SampleCalculation:c = a/v x 1000Concentration1/concentrationManufacturers sample0.0025/7.93 x 10000.3152585120.315 to 3SF3.1723.17 to 3SFSample 10.0025/16.53 x 10000.1512401690.151 to 3SF6.6120000176.61 to 3SFSample 20.0025/25.93 x 10000.0964134210.0964 to 3SF10.3719999710.4 to 3SFSample 30.0025/34.53 x 10000.0724008110.0724 to 3SF13.8119999813.8 to 3SFThe first graph I plotted was average volume of vinegar against the concentration of vinegar. In this graph I have found that the points join up as a curve the graph shows me that the higher the concentration of vinegar the less vinegar needed to neutralize the solution of vinegar and sodium hydroxide. This matches up with my original prediction that The higher the concentration of vinegar the less vinegar needed to neutralize the solution of vinegar and sodium hydroxide. 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.EvaluationIn 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 m ore 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.