Titration Lab Report Essay

The purpose of experiments was to determine the concentration of sodium hydroxide by titrating with KHP and to determine the concentration of Acetic Acid by titrating with a known concentration of sodium hydroxide solution. The titrant is the solution with a known concentration that is titrated to the another solution with an unknown concentration to determine the molarity of the second solution. The analyte is a substance which is examined by analytical procedure; the properties of that solution are measured. In the first reaction the titrant was KHP and the analyte was NaOH, in the second one the titrant was NaOH and the analyte acetic acid.
The first reaction was NaOH + KHP -> NaHP + H2O.
The second reaction was NaOH + CH3COOH -> CH3COONa + H2O

These reactions are the reactions between bases and acids, which are both neutralization reactions and will result in salts and water as the products.

However, there is no color change at end point of these reactions, so an indicator had to be added into the solutions to indicate the end point. An indicator is a chemical which is used to indicate the presence of the another substance in the solution; it changes colors when the ions H+ are added or removed by dissociation reaction. In this experiment, phenolphthalein was used as an indicator to indicate the presence of base in a solution by changing the color of the solution from colorless into pink. When the concentration of H+ is low, the solution becomes pink, and when the concentration of ions H+ is high, it becomes clear. The equivalent point is determined when there is a color change from colorless into light pink, and it is also an approximation of the end point. The concentrations were calculated by the equation M1V1 = M2V2, which means that the moles number of the base must equal to the moles number of an acid. The mole ratio in these reactions are 1:1 that means the moles’ number of the first reactant is equal to the moles’ number of the second one at the end

point.
During the experiments, the unknown concentrations of a base and an acid were calculated through the neutralization reaction. The mole ratio between NaOH and KHP is 1:1, and the ratio between NaOH and CH3COOH also equal to 1:1. In the reaction of NaOH with KHP, the end point’s color of the solution in the trials 1, 3, 5 and 6 were pale pink, and in the trial 2, the solution was light pink. In the trial 4, the end point’s color was dark pink. The trial 4 had a lower NaOH molarity number due to over titration of NaOH solution, the ratio between the volume of NaOH and the volume of KHP solution became unbalanced, and in the result the color of the solution was darker than the colors of the remaining trials. The volume of NaOH used in the reactions was consistent, and it was approximately 17.XX mL; only in the trial 4, the volume was higher, and in the trial 6, the volume was lower than the average volume. The average calculated molarity of NaOH was 0.08724M, which was lower than the actual molarity that equal to 0.09107 M. The percentage of error of the NaOH molarity is equal to 4.206%, and the difference between calculated value and the true value could be caused by a misread of the final and initial buret reading. The standard deviation of the NaOH’s volume is equal to 0.0004 that means the results of NaOH volume makes sense and is acceptable

In the reaction of sodium hydroxide solution with an acetic acid, the end point’s color and the molarity of each trial were less consistent than in the first experiment. In the trials 1, 4 and 5 the color of the final solutions was pale pink, while in the trial 3 and 6 the hue was a little bit darker, and in trial 2 the end point’s color was dark pink. The average acid molarity was 0.164 M, which is higher than the actual molarity. The percentage of error is equal to 7.97%. The percentage error of an acetic acid molarity is higher than percentage error of the base. The difference could be the result of over titrations in the second experiment. The standard deviation, which is equivalent to 0.003, is also higher from the first experiment’s. However, it is still very low and acceptable. In the other words, the data results are located over broader range of values. From the graphs it can be conducted that ratio of the mass (g) of KHP used and the volume (L) of KHP is approximately 107:6, and the ratio of the volume Acetic acid used to the volume of NaOH used in the second experiment is about 4:9.