Zadanie 4d
Suggest two different mixtures, each prepared from the unknown organic acid, that would produce a buffer solution.
Buffer solutions and how they work
Describe the composition of an acidic buffer (weak acid plus its salt) and a basic buffer (weak base plus its salt), and explain with equilibrium equations how each removes added H+ or OH- so that the pH barely changes.
Tę umiejętność sprawdza 15 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Zadania sprawdzające tę umiejętność: 15 Otwórz w wyszukiwarce z filtrami
Zadanie 5b
A buffer solution can be prepared by mixing NH3(aq) with HCl(aq). (i) Describe how the two solutions should be combined so that the buffer obtained is as effective as possible. (ii) Write equations to show how this buffer solution responds to the…
Zadanie 3g
(i) Describe how aqueous hexanoic acid and aqueous sodium hydroxide could be used to make a buffer solution. (ii) Predict the effect on the buffer's pH of adding a small amount of water.
- Materiał graficzny
Zadanie 3c
Hypochlorous acid, HOCl(aq), has Ka = 2.95 × 10−8. (i) Determine the pH of an aqueous solution of hypochlorous acid of concentration 0.150 mol dm−3. (ii) State one assumption you made in the calculation in (i). (iii) State…
Zadanie 20b
A buffer solution of pH 5.35 contains ethanoic acid and its conjugate base, the ethanoate ion. The pKa of ethanoic acid is 4.76. The concentration of ethanoic acid in the buffer is 1.50 × 10−2 mol dm−3. Calculate…
Zadanie 27
Which combination would produce a buffer solution? A. 50 cm3 of 1.0 mol dm−3 NH3(aq) and 50 cm3 of 1.0 mol dm−3 HCl(aq) B. 25 cm3 of 1.0 mol dm−3…
Zadanie 30
The pH curve below is produced when 25.0 cm3 of ethanoic acid of concentration 0.100 mol dm−3 is titrated with sodium hydroxide solution of concentration 0.100 mol dm−3. Besides water and sodium ions, which species…
- Materiał graficzny
Zadanie 26
Consider the buffer system made from ethanoic acid and sodium ethanoate, CH3COOH / CH3COONa. What happens when a small amount of strong acid is added to the buffer? A. [CH3COOH] increases. B. [CH3COO−] increases. C. The H+…
Zadanie 1c
A neutralization curve for a weak acid, HA, titrated with a strong base is shown. (i) Estimate the pKa of HA. (ii) Explain, using an equation, why the pH changes very little when small volumes of strong base are added to the weak acid in the buffer…
- Materiał graficzny
Zadanie 26
Which mixture forms an acidic buffer solution? A. 25 cm3 of 0.10 mol dm−3 NaOH added to 50 cm3 of 0.10 mol dm−3 ethanoic acid B. 25 cm3 of 0.10 mol dm−3 NaOH added…
Zadanie 26
Equal volumes (20.0 cm3 each) of two solutions are mixed. Which pair gives a buffer solution? A. 0.20 mol dm−3 CH3COOH and 0.10 mol dm−3 NaOH B. 0.10 mol dm−3 CH3COOH and…
Zadanie 26
100 cm3 of each of two solutions are mixed. Which pair of solutions gives a buffer? A. 0.10 mol dm−3 CH3COOH and 0.10 mol dm−3 NaOH B. 0.20 mol dm−3 CH3COOH and…
Zadanie 4c
The base dissociation constant of methylamine at 298 K is Kb = 4.4 × 10−4. (i) Calculate the concentration of hydroxide ions in a methylamine solution with pH = 11.6. Use sections 1 and 2 of the data booklet. (ii) Calculate the concentration, in…
Zadanie 7a
(i) State why ammonia can act as a Lewis base. (ii) Calculate the pH of a 2.50 × 10−2 mol dm−3 aqueous solution of ammonia. pKb = 4.75 at 298 K. (iii) Justify whether a 1.0 dm3 solution made by mixing 0.30 mol NH3…
Zadanie 26
Which pair of solutions will form a buffer when mixed? A. 25 cm3 of 0.20 mol dm−3 HCl and 25 cm3 of 0.20 mol dm−3 NaOH B. 25 cm3 of 0.20 mol dm−3 NH3…