Interpretation Of Data.docx

Interpretation of Data Standardizing the NaOH Standardizing the NaOH solution. The students used potassium hydrogen phthalate (KHP) as the primary standard. A KHP of known mass therefore known moles can be titrated with the NaOH solution to precisely the concentration of the NaOH. KHP has one acidic hydrogen atom, and reacts with NaOH on a 1:1 stoichiometric basis

Since 0.1g of KHP was used in all three trials and the molar mass of KHP is 204.6g. The amount of moles of KHP can be determined using the formula below. Since the mole ratio is 1:1 the number of moles of KHP also represent the amount of moles NaOH can react with moles of KHP which can be found in Table 2. Once the volume of NaOH is found, the number of moles of KHP and the stoichiometric ratio is used to find the molarity of NaOH. Which can be found in Table 1. 𝑚𝑎𝑠𝑠 𝐾𝐻𝑃 = 𝑚𝑜𝑙 𝐾𝐻𝑃 𝑀 𝐾𝐻𝑃 The average concentration for NaOH is 0.09725 M NaOH. The desired concentration for NaOH is 0.1 M which is near the average concentration of NaOH that have been obtained from the lab with a percent error of 2.75% which was calculated using the formula below.

Table 3. Number of moles of KHP and NaOH Trial 1 Number of moles of KHP (mol) Number of moles of NaOH that can react with KHP (mol)

Trial 2

Trial 3

0.000489 mol KHP

0.000489 mol KHP

0.000489 mol KHP

0.000489 mol NaOH

0.000489 mol NaOh

0.000489 mol NaOH

Using the mole ratio of NaOH and KHP equivalence point can be reached. The equivalence point tells the volume needed of the unknown concentration NaOH solution for the KHP and NaOH to react in a stoichiometric ratio. At the equivalence point stoichiometric amounts of KHP and OH - have been mixed. The product KP- is a weak base. Just past the equivalence point, KHP is limiting, and so OH- is left over therefore the solution is basic. The equivalence point is determined by the end point which is the point where the sudden change in color occurs using the indicator Phenolphthalein that changes color as the solution changes from acidic (Colorless) to basic (Pink). This type of titration use to determine the concentration of NaOH is called Colorimetric Titration which relies on the sudden change of color by using an indicator when the pH of the solution changes

Standardizing the HCL In standardizing the titrant (HCl Solution) the students used the ~0.1M NaOH using phenolphthalein as the indicator. This type of titration uses a neutralization reaction, in which an acid and a base react to produce a salt and water. pH level of the reaction is approximately at 7 due to reagents being strong in their respective field.

Using the equation above the stoichiometric ratio of HCL and NaOH is determined to be 1:1. the ratio was used to achieve the equivalence point determined by the end point at which color suddenly changes indicator used Phenolphthalein from basic (Pink) to Neutral/Acidic (Clear). Average concentration of the three HCl trials is 0.10570 M HCl obtained from the lab the desired concentration is 0.1 M HCl which is approximately near desired concentration that has a 5.7% error calculated using the percent error formula