Acid Base Titration Lab Report Conclusion

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Title:
The use of volumetric flask, burette and pipette in determining the concentration of NaOH solution.

Objective:
• To carry out acid-base titration.
• To determine the end point with the use of indicators such as phenolphthalein.
• To find out the concentration of base when the concentration of acid is known.
• To do calculations related to titration.

Theory and Background:
Titration is a laboratory analytical method to determine the concentration of a solution or a reactant when the concentration of another solution is known. Acid-base titration is a method often used to determine the concentration of a basic solution, given the concentration of an acidic solution is known and vice versa.

When a strong base, for example sodium
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Analysis and Calculations
The experiment is a strong acid-strong base titration. From this experiment, we can analyze concentration of base when the concentration of acid is known. The HCl solution, added with a few drops of phenolphthalein, is placed into the Erlenmeyer flask and the NaOH solution is slowly added from the burette into the HCl solution in small drops. Neutralization occurred in the titration process:

NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l)

This reaction shows that 1 mol of NaOH will react with 1 mol of HCl to produce 1 mol of the salt (NaCl) and 1 mol of water.
Phenolphthalein indicator is used to determine the end-point of the titrated solution. It can be determined when the colourless titrated solution changes to pink colour
After we recorded the readings from the burette, we need to calculate using the given formula and the average volume of NaOH solution used from the results.

Take II, III, IV result,
Average volume of NaOH solution
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From the above calculations, we can conclude that the results of titration III is the most accurate as it is less than 3 as stated above, which is 1.059.

Discussion According to our results above, the readings obtained for the 4 titrations are not very constant. The reading obtained for the first experiment has a big difference when compared to the other three readings. This may be because we didn’t catch the end point for the first experiment. As for the other three readings, they are not very constant as we catch the end point differently for each titration. The colour of the solution might be slightly different at the end of each titration.

Theoretically, the volume of base needed to neutralize the acid should be the same as the volume of the acid. The volume of acid used in this experiment is 25 cm³. So the volume of base needed to neutralize the acid will be also 25 cm³. According to our results, all the readings fell far short of the original reading. This may be cause by the extra amount of phenolphthalein indicator added into the acid, causing it to turn pink faster. Another reason is that we did not catch the end point

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