Use the information provided to (a) fill in the table below and (b) show your calculations for 1 trial below the table. The experiment conducted in this part is a titration using KHP as the primary standard to titrate a solution of NaOH of unknown concentration. The experimental procedure is as described on pages 46- 47 of the lab manual. To correctly perform the calculations asked for below, focus on the following:
1. Identify exactly what acid and base reagents are used. Determine molar mass of KHP for gram to mole conversion.
2. Use a balanced reaction for the titration to determine the mole to mole ratio of acid to base (see lab manual).
3. Use this mole to mole ratio as well as the mathematical relationships between moles, volume and molarity to determine the molarity of NaOH for each trial below.
4. For all molarity calculations, you will need to work in liters, as M = mol/L
5. 6 samples of KHP were titrated with NaOH of unknown concentration to the equivalence point. Perform the necessary calculations and fill in the table found below.
Experimental Data
Trial # Mass of Moles of Volume of Molarity of
KHP KHP NaOH dispensed NaOH,
titrated titrated at the end point calculated (mol/L)
1 0.480 g 21.89 mL
2 0.485 g 21.89 mL
3 0.491 g 22.28 mL
4 0.497 g 22.77 mL
5 0.503 g 22.79 mL
6 0.513 g 23.48 mL
Average
Molarity:
Show calculations for trial 1 only used for the following:
Moles of KHP in trial 1:
Molarity of Sodium Hydroxide solution in trial 1:
1. What is Potassium Hydrogen Phthalate and why is it used for standardization of an NaOH solution?
2. In a similar experiment to Part I, a solution of calcium hydroxide of unknown concentration is standardized against potassium hydrogen phthalate (KHP). From the data below, calculate the molarity of Ca(OH)2 solution. The balanced reaction is:
Ca(OH)2 + 2KHC8H4O4 à CaC8H4O4 + K2C8H4O4 + 2H2O
Note the 1:2 mole to mole ratio of calcium hydroxide to KHP.
Mass of KHP consumed at titration end point: 0.914 g
Ca(OH)2 titrated to reach endpoint: 26.42 ml
3. Determine how many liters of the standardized Ca(OH)2 in question 2 will be needed to neutralize an aqueous solution containing 0.1453 g of oxalic acid dihydrate (126.07 g/mol). The balanced reaction is:
H2C2O4 + Ca(OH)2 → CaC2O4 + 2 H2O