6. A101s.q sample of KHP (o0uo g/mol) is dis. NaOH solution to a phenolphthalein

Question

6. A101s.q sample of KHP (o0uo g/mol) is dis. NaOH solution to a phenolphthalein endpoint. Reter o the molarity of the solution. to g/mol) is dissolved in water and titrated with 24.55 ml NaOH solutionein endpoint. Refer to Example Exercise 1 and calculate 7. A 10.0-mL vinegar sample is pipetted into sample is pipetted into an Erlenmever flask and titrated with 41.60 mL of 0.202 M NaOH to a phenolphthalein endpoint (a) Refer to Example Exercise 2 and calculate the molarity of the acetic acid in the vinegar. (b) Assume the density of the vinegar solution is 1.01 g/m L and find the mass/mass percent concentration of acetic acid, HC2H302 (60.06 g/mol), in the unknown vinegar sample. 8. Which of the following is a serious source of experimental error? (a) The sodium hydroxide is not mixed completely in the Florence flask. (b) The buret is not conditioned. (c) The KHP samples are dissolved in 50 mL (not 25 mL) of distilled water. (d) Two drops (not one drop) of phenolphthalein indicator is used (e) Bubbles are not cleared from the tip of the buret. (0) The Erlenmeyer flasks are not dry before pipetting the vinegar samples.

Explanation / Answer

According to chegg rules we have to answer only first one problem

6.

Balance reaction:

NaOH(aq) + KHC8H4O4(aq) ---> H2O(l) + KNaC8H4O4(aq)

Mole of KHP = 1.015 g/ 204.23 g/ mole

= 0.00497 moles KHP

Now calculate the moles of NaOH:

0.00497 moles KHP *1/1

0.00497 moles NaOH

Molarity = number of moles / volume in L

= 0.00497 moles NaOH/ 0.02455L

= 0.202 M

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