The reaction represented above occurs when 2.00 × 10–4 mol of pure acetylsalicylic acid, C 9 H8O 4 , is completelydissolved in 15.00 mL of water in a flask and titrated to the equivalence point with 0.100 M NaOH(aq). Whichof the following statements about the titration is true at the equivalence point?(A) [C9H 8O 4] is greater than [C9H 7O 4].(B) [C9H 8O 4] is less than [C9 H7O 4 ] .(C) [C9H 8O 4] is equal to [C9 H7O 4].(D) The relationship between [C9H 8O 4] and [C 9H 7O 4] cannot be determined without additional information.Unauthorized copying or reuse ofany part of this page is illegal. GO ON TO THE NEXT PAGE.-21-
Question
The reaction represented above occurs when 2.00 × 10–4 mol of pure acetylsalicylic acid, C 9 H8O 4 , is completelydissolved in 15.00 mL of water in a flask and titrated to the equivalence point with 0.100 M NaOH(aq). Whichof the following statements about the titration is true at the equivalence point?(A) [C9H 8O 4] is greater than [C9H 7O 4].(B) [C9H 8O 4] is less than [C9 H7O 4 ] .(C) [C9H 8O 4] is equal to [C9 H7O 4].(D) The relationship between [C9H 8O 4] and [C 9H 7O 4] cannot be determined without additional information.Unauthorized copying or reuse ofany part of this page is illegal. GO ON TO THE NEXT PAGE.-21-
Solution
The question seems to be about a titration process involving acetylsalicylic acid (C9H8O4) and sodium hydroxide (NaOH). At the equivalence point of a titration, all of the initial substance (in this case, acetylsalicylic acid) has reacted with the titrant (NaOH). This means that there should be no unreacted acetylsalicylic acid left in the solution, so the concentration of C9H8O4 should be zero.
On the other hand, the product of the reaction between acetylsalicylic acid and NaOH is the conjugate base of the acid (C9H7O4-) and water. Therefore, at the equivalence point, the concentration of C9H7O4- should be at its maximum.
So, the correct answer to the question would be (B) [C9H8O4] is less than [C9H7O4-].
Similar Questions
What is the pH at the equivalence point for the titration between sodium hydroxide and acetic acid?
A student titrates 10.0 mL samples of 1.0 Msolutions of each of the haloacetic acids with astandard solution of NaOH. Which of thefollowing statements correctly predicts thevolume of NaOH(aq) needed to reach theequivalence point?(A) Fluoroacetic acid will need the smallestvolume of NaOH(aq) to reach theequivalence point.(B) Iodoacetic acid will need the smallest volumeof NaOH(aq) to reach the equivalencepoint.(C) All of the acids will need the same volume ofNaOH(aq) to reach the equivalence point.(D) All of the haloacetic acids are weak; thereforenone will reach an equivalence point.Unauthorized copying or reuse ofany part of this page is illegal. GO ON TO THE NEXT PAGE.-16-
Measurements for the titration of acetic acid with NaOHEnter your measurements from lab for trails 1 - 3 with the correct number of decimal places Trial 1Trial 2Trial 3Mass of empty flask (grams)71.39171.42572.095Mass of flask + vinegar (grams)81.00381.37982.014Volume of vinegar (L)0.010000.010000.01000Concentration of NaOH (mol/L)0.20000.20.2Initial volume of NaOH (mL)0.600.290.20Final volume of NaOH (mL)41.6541.9441.53AttendanceThis QR code needs to be scanned by your TA to confirm that you have completed data collection and cleaned up your workspace.Done online(51pts) CalculationsTitration of Acetic Acid with NaOHCalculations for the titration of acetic acid with NaOHTable view List viewComplete the calculations below for trials 1 - 3 with the correct number of decimal places Trial 1Trial 2Trial 3Mass of empty flask (grams)71.39171.42572.095Mass of flask + vinegar (grams)81.00381.37982.014Mass of vinegar (grams)Volume of vinegar (L)0.010000.010000.01000Concentration of NaOH (mol/L)0.20000.20000.2000Initial volume of NaOH (mL)0.600.290.20Final volume of NaOH (mL)41.6541.9441.53Volume of NaOH added (mL)Volume of NaOH added (L)Moles of NaOH used (mol)Moles of acetic acid (mol)Mass of acetic acid (grams)Mass percent of acetic acid(9pts)Average mass percent(9pts)Standard Deviation
A chemistry student weighs out 0.131g of acrylic acid HCH2CHCO2 into a 250.mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1800M NaOH solution.Calculate the volume of NaOH solution the student will need to add to reach the equivalence point. Round your answer to 3 significant digits.
For the titration of a strong acid with a strong base, the equivalence point at which base completely neutralizes the acid has a pH of 7.0. Select and justify your choice of an indicator that will allow you to visually determine the equivalence point.
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