Assessed Practical Titration Write-Up

The actual titration recording formula was evaluated: Na 2 CO 3 + H 2 SO 4 → Na 2 SO 4 + CO 2 + H 2 O 1 mol of Na 2 CO 3 was reacted with 1 mol of H 2 SO 4. Results: The weight of my sodium carbonate crystals is 67 g, and titration results are as follows: Coarse 1st 2nd 3rd 4th 5th 6th 1st reading 00.00 00.50 00.00 00.00 00.00 00.20 Final reading 26.45 26.45 26.05 27.00 25.85 25.90 26.10 Titrimetric method 26.45 25.95 26.05 27.00 25.85 25.90 25.90 pH Weakly acidic neutral Weakly acidic weakly acidic weakly alkaline neutral

The purpose of this experiment is to deepen the understanding of the practical application of back titration. Counter titration is designed to solve the problems encountered with positive titration. There are many reasons why the back titration method can be used: if the specimen is volatile or insoluble in water, if the specimen contains impurities that interfere with positive titration, if it is difficult to identify the end point with positive titration, In case of positive titration When reacting slowly with titrant. In this experiment, the weighted portion of the toothpaste was analyzed to determine the mass percentage of CaCO 3 present in the toothpaste sample. This experiment uses reverse titration technique instead of forward titration. This is because the toothpaste which is the substance to be analyzed is insoluble in water but soluble in acid.

The main objective of this experiment was to determine the proportion of calcium carbonate in toothpaste by using reverse titration instead of forward titration and standard titration as calcium carbonate is insoluble in water . The average percentage of calcium carbonate in toothpaste was 19.97%. The result is relatively close to the theoretical value of 20%. The result is constant and close to the theoretical value, so this experiment is considered successful. Therefore, most errors should be avoided.

The purpose of this experiment was to determine the proportion of calcium carbonate in toothpaste using back titration. Instead of using a standard titration method where the acid is directly titrated using a base solution of base, back titration is used as the sample CaCO 3 to be analyzed is insoluble in water. Hydrochloric acid and sodium hydroxide are reagents used in this experiment. A precisely measured amount of HCl is added to the weighted portion of CaCO 3 of the toothpaste. When the reaction between HCl and CaCO 3 was complete, the excess HCl was back-titrated with NaOH until the reaction reached the end point and the indicator changed from pink to orange. Therefore, the amount of HCl reacted with CaCO 3 can be calculated by using an initial excess of HCl to subtract the amount of HCl remaining after the reaction.