Select a suitable indicator from the data booklet whose pH range matches the equivalence point pH predicted from the salt formed, and distinguish the end point (indicator colour change) from the equivalence point (stoichiometric completion).
Tę umiejętność sprawdza 9 zadań wzorowanych na arkuszach IB z lat 2022–2026.
The titration curve below was obtained when the sodium hydroxide solution was added to 25.0 cm3 of the unknown organic acid in part (b). State, with a reason, which indicator would be appropriate for this titration, using section 18 of the data booklet.
What is the best indicator to use in the titration of propanoic acid with potassium hydroxide? A. Methyl orange, pKa = 3.7 B. Bromocresol green, pKa = 4.7 C. Bromothymol blue, pKa = 7.0 D.…
The pH curve below was obtained when sodium hydroxide solution was added to a sample of ethanoic acid until the base was in excess. Which indicator would be most suitable for this titration? A. Methyl red, pKa = 5.1 B. Phenolphthalein,…
The student then used the potassium hydroxide solution standardized in 1c to titrate ethanoic acid, CH3COOH, whose concentration was not known. (i) Neutralizing 25.00 cm3 of the acid required 40.00 cm3 of the standardized…
Hexanoic acid, CH3(CH2)4COOH, is a weak acid. The graph shows how the pH changes during the titration of a 20.0 cm3 aqueous solution of hexanoic acid with aqueous sodium hydroxide. (i) Deduce an expression for the equilibrium constant, K,…
In a titration, 25.0 cm3 of 0.100 mol dm−3 ethanoic acid, CH3COOH, was placed in a flask and 0.100 mol dm−3 sodium hydroxide solution was added from a burette. The pH curve is shown. (i) Using section 18 of the…
In a titration, 25.00 cm3 of a 0.120 mol dm−3 solution of a weak monoprotic organic acid, HA, was neutralized by adding sodium hydroxide solution, NaOH(aq), from a burette. The pH curve obtained is shown. (i) Determine the…
The concentration of an ethanoic acid solution was found by titration with a 0.150 mol dm−3 standard solution of potassium hydroxide, KOH(aq), using an indicator to detect the end point. (i) Calculate the pH of the potassium hydroxide solution.…
A 0.50 mol dm−3 solution of ammonium chloride is prepared. (i) Calculate the pH of an ammonium chloride solution with [H3O+] = 1.68 × 10−5 mol dm−3. Use section 1 of the data booklet. (ii) Write the equation for the…
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