Part C – Titration of Prepared Acid Solution 7. A sample of the prepared HCl was measured in a graduated cylinder and transferred to a flask with phenolphthalein indicator. 8. HCl sample was then titrated to endpoint using the standardized NaOH solution. HCl stock soln = 0.103 M Part A #1 HCl (mL) NaOH (mL) initial 0.00 0.15 final 26.12 27.60 Endpoint was a clear, very faint pink solution. Part A #2 HCl (mL) NaOH (mL) initial 0.48 0.40 final 25.55 27.16 Clear, very faint pink solution. Calculate how many mL of 6 M HCl you need in order to make 250 mL of your assigned concentration. Show your work to receive credit. Part C HCl (mL) NaOH (mL) initial 23.0 1.20 final Clear, very faint pink solution.
2 DATA ANALYSIS Standardizing the NaOH Solution (Part A) a. Determine how many liters (L) of stock HCl were used in titration #1. b. Determine the number of moles of HClin this volume of solution. (Hint: you will need to use its concentration to calculate this.) c. Determine the number of moles of NaOH. (Hint: you will need to know the chemical relationship of HCl to NaOH; i.e. its stoichiometry.) d. From the volume of NaOH used in titration #1, determine its molarity (M)e. Repeat steps a-d for your second trial and average the two values for molarity of NaOH. Determining the Titration Values of Prepared HCl (Part C) f. Based on your assigned HCl concentration, determine the number of moles of HClin the sample used for titration. (Pay close attention to your units!) g. Determine how many moles of NaOHwere used to titrate this sample. h. Determine what volume of NaOH this required, in liters (L)i. Determine what the final reading on the buretmust have been, in milliliters (mL), and enter it into the blank box on the table for Part C. . .
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- Fall '08