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Finding the Concentration of Hydrochloric Acid by Titration.

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Finding the Concentration of Hydrochloric Acid by Titration Na2CO3 + 2HCl = 2NaCl + H2O + CO2 The sodium carbonate in this solution is what we call the standard solution as it is the one which we know the concentration of accurately. This is because we have measured out an amount of sodium chloride (solid) to 1/100th gram, and then put this into a 100ml volumetric flask which was filled exactly to the 100ml mark. Mass of weighing boat: 1.325 Mass of weighing boat and sodium carbonate 3.942 Total weight 5.262 Sodium chloride is neither deliquescent nor efflorescent. This means that it does not take in water from the atmosphere, nor does it give out water to the atmosphere. This means that the mass is purely sodium chloride and nothing else.Na2CO3 has a relative formula mass of 106g. Method When the contents of the weighing boat was poured into the small beaker it was important to add the distilled water very slowly so that a paste was formed. Once the paste was formed more distilled water could be added so that the solution could be made. ...read more.


The small beaker was then washed out with a small amount of hydrochloric acid to ensure that none of the water was left behind. The same thing was done for the burette. The burette was then filled with about 40ml of hydrochloric acid. This was left for about one minute to ensure that all of the hydrochloric acid has settled in the burette and that none was still on the sides of the tube. Once it had sufficiently settled the reading was taken, this reading is the initial burette reading. Again it is important to take the reading which is at the bottom of the meniscus! The conical flask was then washed out with distilled water. Using the pipette exactly 10ml of the sodium chloride solution was then transferred into a conical flask. The bottom of the meniscus should be on the mark for 10ml. When transferring this into the conical flask a tiny amount of solution will be left in the pipette which is impossible to get out. However you must ensure that you get as much solution out as possible by touching the end of the pipette into the solution which is in the conical flask. ...read more.


This reading must be taken from the bottom of the meniscus.: The whole experiment is repeated three times to get accurate results. Experiment 1 2 3 Initial burette reading 0.7 0.75 0.6 Final burette readingc 27.5 27.8. 28.0 Difference between two burette readings 26.8 27.05 27.4 Experiment number 1 and 2 gave accurate results, number 3 however was 0.1 off of the other two. Therefore I shall take the average only of experiment numbers 1 and 2 and use these to calculate the concentration of the hydrochloric acid. The average of 26.8 and 27.05 is 26.925. Na2CO3 + 2HCl = 2NaCl + H2O + CO2 One mole of Na2CO3 reacts perfectly with two moles of HCl. I used 10ml of a 25 dm3 solution of Na2CO3. This reacted with exactly 26.925ml of an unknown concentration solution of HCl. Being as one mole of sodium carbonate reacts with two moles of hydrochloric acid we can divide 26.925 by 2 to get the value of one mole of hydrochloric acid. This gives us 13.462 Therefore: 10ml x 26.925 = 269.25 13.462 x 269.25/13.462 = 0.269 The concentration of the hydrochloric acid is therefore 0.269/dm3. ...read more.

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