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In this experiment I am finding out how much sulphuric acid is present in sodium carbonate solution.

Extracts from this document...

Introduction

AS Chemistry Coursework Aim: In this experiment I am finding out how much sulphuric acid is present in sodium carbonate solution. How I will find the accurate concentration of sulphuric acid I am to find the accurate concentration of sulphuric acid ranging between 0.05 and 0.15-mol dm-3, I am provided with solid, anhydrous sodium carbonate, and range of indicators. The indicator which I will be using in my experiment is methyl orange, because it is used in most titrations, and it changes colour as a mid strength acid. It has sharper end point then universal indicators. The pH of methyl orange is 3.1 - 4.4. This is the chemical balanced equation that will take place, during my experiment. Equation: H2SO4 (aq) + Na2COaq) � Na2SO4 (aq) + H2O (l) + CO2 (g) From looking at the equation we can see that one mole of aqueous sulphuric acid reacts with one mole of sodium carbonate. (These are the reactants). This forms the (products) which is one mole of aqueous sodium carbonate, one mole of water and one mole of carbon dioxide. The balanced chemical equation is in a 1:1 ratio. Choosing the concentration of sodium carbonate solution The concentration of sodium carbonate which I will choose will be 0.1 mol dm-3, I have chosen this concentration because it is halfway between 0.05 and 0.15 moldm-3 of sulphuric acid concentration, I added, 0.05 and 0.15 and found out the average concentration which I could use was 0.1 mol dm-3, this has therefore given me a basic idea that my sodium carbonate solution should be ranging near that concentration. I will be making a 250cm3 solution. Working out the mass of sodium carbonate used 1000cm3 is equivalent to 1dm3. I need to convert 250cm to dm3. This is done by dividing 250cm by a 1000 (250 1000), which equals to 0.25dm3. Now I have worked out the volume of anhydrous sodium carbonate needed is 0.25dm3. ...read more.

Middle

Use a white tile to see the colour change accurately. 12. The sulphuric acid drops should stop being added until there is a permanentnt colour change in this case the colour change from yellow to pink. Distilled water should be used to rinse the inside of the conical flask, since swirling may have unrelated sulphuric acid on the walls. If the colour change persists add one more drop of sulphuric acid (just to be sure) and then stop. Record the ending burette volume in the data table it should be recorded to at least 2 decimal places to maintain accuracy of the reading, at this point this will allow you to find an approximate value for the volume of sulphuric acid needed to react with the sodium carbonate solution. 13. Before repeating the titrations all apparatus should be cleansed with distilled, water, this includes the conical flask, the burette, and the pipette to avoid contamination and to get of any impurities. 14. The titration should be repeated a number of trials (possibly 4-5 trials) and. Repeat the titration until they are reliable and concordant results are obtained, (concordant means, results are very similar to each other, and there are no analomies present), that will allow you to find the accurate concentration of the acid solution. 15. For clean up the, contents should be dumped down the drain with Plenty of running water. All apparatus should be rinsed and burette Should be clamed upside down with the stopcocks open? Weight of boat and sodium carbonate together is 3.77g. Therefore to find the mass of the boat it is: 3.77- 2.64 = 1.13g Mass Sodium Carbonate 2.64g Weighing boat 1.13g Risk Assessment Chemical Procedure Hazard How to reduce risk Disposal Source of advice Sodium carbonate Irritant Wear safety goggles, and wear lab coat. Avoid skin contact In the case of spillages, skin contact, eye contact rinse immediately with water. ...read more.

Conclusion

A wrong reading of the meniscus can lead to a inaccurate result, and the results will not be concordant. . Pipette errors A pipette should be used with a perfect tip. A pipette, which has a broken or chipped tip, must be discarded since it will deliver a volume other then the rated volume when the tip is touched against the wall of the receiving vessel. Before I added, the sodium carbonate solution, I made sure that I wiped of any drops adhering to the outside of the pipette as this prevents droplets from the outside from draining into the receiving vessel (conical Flask), and affecting the results. I made sure that the pipettte was recleaned immediately before use, because if it stands more than an hour under ordinary conditions there is the possibility of air-contamination, which will affect my results. Overall my results are accurate, and concordant. During my titration experiment, I had gained two anomalous results, which were not concordant; I rejected these anomalous results, when calculating my average, as taking the anomalous results when calculating the average titre, would give me inaccurate results, when working out the concentration of sulphuric acid. The anomalous results are shown in the table below. Starting point End point Titre volume(dm3 Trial 5 0 20.35 20.3-0=20.3 Trial 6 0 21.45 21.4-0=21.4 In order to gain even more accurate concordant, results, each student could of had, a new batch of Sulphuric acid, although I made sure, that the solution was not contaminated, and used apparatus which were clean, and had been rinsed, I can not be sure, that other students, may have contaminated the sulphuric acid, solution, or the diluted water, this was beyond my control. Adding impurities, could affect my results, and lead to slight inaccuracy. In most titration experiments, a number of trials are done; I had only done one rough trial and 3 trials, following this. In order to gain even more concordant results I would have to conduct more trials, as increasing the number of trials will gain a more accurate end point. ...read more.

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