Titrations are a quantitative chemical analysis technique. They are done to tell us how much acid is required to neutralise a certain quantity of alkali. A titration is a technique in which a solution of reactant (the titrant) is added to a solution of a second reactant (the analyte) until the end point is reached. The end point of the titration is the point at which the titrant has been added in the right quantity to neutralise the analyte. Usually you can see this by adding a reagent in the analyte, which is an indicator. The indicators, which are the most common, are phenolphthalein and methyl orange. Phenolphthalein turns the analyte red when you add it and it turns colourless once the titration is complete. Methyl orange turns yellow when you add it in the analyte and then turns red once the titration is complete.
Titrations are used in a lot of different industries and all have different reasons for their use. Examples of where titration can be used in industry are; wineries, dairy farms, mining corporations, cleaning material manufacturers, drink makers, food makers, cosmetic industries, health industries, water plants and pharmaceuticals industry. Most industries that work with pH levels would use titrations to ensure that we as humans can consume them or to check if we can come into contact with them.
Water plants would use titrations to check how pure the water is and to see if drinking it would cause any harm to us as humans. They would also use titrations to find out the purity of a pond or a lake. This could be done because a lot of the fish or frogs are dying and by doing this you can find out what the reason may be.1
Drink makers would use titration when they are producing their drinks to find out the acidity of their product and by doing this they could give the consumer the right nutritional information. Both drink makers and wineries would use this for the same reason.1
When you do a titration you have to do a calculation to find out the concentration of the unknown chemical, which is being neutralised by the alkali.
For this investigation I was given some ibuprofen that was found on the main suspect and Dr Bell and I had the task to titrate both of the samples to see if they matched. I was given everything that I need for the investigation but I had to make up the standard solution (analyte). I will talk about how I made this further on in this investigation.
My aim for this investigation was to learn about using titrations and apply it to the case I was working on. I used what I have learned and applied it to the case of Dr Bell.
Pippete: I used this fill up 25cm3 of the NaOH and put it into the conical flask. I used this because it is very accurate. Burette: I used this to titrate the NaOH. I poured my standard solution into this, as this is very accurate too. Volumetric Flask: I used this to make my standard solution in and kept it in there as again this is very accurate and makes a precise amount. Conical Flask: I poured the 25cm3 of NaOH into this and then put the indicator in it and then put it under the burette. Distilled Water: I used this to clean out my conical flask after every use and also used this to make up the standard solution. White Tile: I put this under the conical flask, as this would make me see any colour change more clearly. Phenolphthalein Indicator: I used this as my indicator so I could determine the colour change and therefore determine the exact point the NaOH was neutralised. Pipette Fillers: I put this on the pipette and this sucked up the NaOH. This has three buttons on it, which do different things when you press them. One of them sucks up the NaOH, one release it and one releases all the air out of the filler; this allows it to suck up more. Pastille and crusher: I used this to crush my ibuprofen.
Funnel: I used this to move the crushed ibuprofen from the pastille to the volumetric flask.
1.Firstly I had to clean out all of my equipment with distilled water. 2.I then crushed 2 ibuprofen tablets in a pastille and crusher until it was finely ground. 3.I then moved it from the pastille into the volumetric flask by using a funnel. 4.I then used the distilled water to make sure all of the ibuprofen was in the volumetric flask. 5.I then filled the volumetric flask up with distilled water to make up the standard solution. 6.I then filled the burette with the standard solution up to the 0cm3 mark. 7.I then took the air out of the pipette filler by holding down a button and pressing the filler. 8.I then put the pipette filler onto the pipette.
9.I then sucked in the NaOH into the pipette until it got to the 25cm3 10.I then released all of the NaOH into the conical flask.
11.I then added 3 drops of the universal indicator into the conical flask. 12.I then placed the white tile onto the base of the burette stand and put the conical flask onto it. 13.I then added the standard solution slowly to find out roughly what answers I was looking for. 14.I then repeated steps 6 through to 13 for each titre.
TitrationInitial cm3Volume cm3Volume added cm3
Green highlight is anomalous.
To work out the concentration of the unknown sample I had to some calculations and this is how I did them. The first step was to find out the molecular mass of ibuprofen and sodium hydroxide; ibuprofen is 206g and sodium hydroxide is 40g. Once I had got this I had to work out the number of moles that I had and to do this I had to use the equation Mass= Mr x Mole. I had to rearrange the formula so that it read Mass/Mr= Mole. This then gave me the answer of 0.019moles. I did this by doing 4g/206g. I divided 206g by 4g because I was using 400mg of ibuprofen and to put that into the equation I had to divide it by 100 because I need it in grams. I then had to use a different equation and this time I used the N=C x V. Which stands for Number of moles (which I have worked out previously) equals to the concentration in moldm-3 times by volume in dm3. I then had to rearrange the formula to find out the concentration, as this was my aim of this investigation. My equation then read N/V=C which once filled out read 0.019moles/12.9 cm3=0.0014moldm-3. I got the 12.9cm3 from my titration results.
•Mass/Mr= Mole = 4g/206g=0.019mols
N=C x V
•N/V = C = 0.019/12.9 = 0.0014moldm-3
Overall I feel as if my experiment was a success as I did everything I was supposed to do in the best possible way. Another reason why I think my experiment was a success is because there were no spillages or any mistakes made by me when I had to make my standard solution. I also think that my results are reliable and valid as I repeated the experiment four times as I got an anomalous result. I also feel that I used all of the equipment really well, as I didn’t create any spillages or any hazards. The main factor for this was the fact that I had a little bit of practice when it came to doing the titration as I have done titrations before. In case of an emergency we had a lot of safety measures already in place for example if there was a spillage we had paper towels at hand to clean the spillage up quickly before an accident occurred.