A 0.010 mol dm-3 solution of a weak acid HA has pH = 4.00. What is the value of Ka?
Use Ka is approximately equal to [H+]^2 / [HA].
At 25 degC, the pH of pure water is 7.00. What is the pH of pure water at 60 degC?
Water's ionisation is endothermic, so Kw rises with temperature.
A pH higher than 7 means a hydronium ion concentration:
Higher pH means fewer H+ ions.
What is the [H+] in a solution with pH = 4.52?
Which solution would have the highest pH?
A strong alkali produces the most OH- ions.
At 40 degC, the ionic product of water, Kw, is 2.9 x 10^-14 mol2 dm-6. What is the pH of pure neutral water at this temperature?
In pure water, [H+] = sqrt(Kw).
Which one has the lowest pH value?
This acid releases two H+ ions per molecule.
A solution has pH = 3.00 at 298 K. Which statement is correct?
Which statement about pKa is correct?
pKa and acid strength are inversely related.
What is the pH of a 0.0050 mol dm-3 solution of Ba(OH)2? (Kw = 1.0 x 10^-14 mol2 dm-6)
Each mole of Ba(OH)2 gives two moles of OH-.
Which is the correct expression for the first acid dissociation constant, Ka1, of hydrogen sulfide, H2S?
The first dissociation removes only one proton.
Which of the following statements about Kw is correct?
The ionisation of water is endothermic.
Acid X has pKa = 2.0. Acid Y has pKa = 5.0. Which statement is correct?
Each pKa unit represents a factor of 10 in Ka.
The pH of a 0.10 mol dm-3 solution of a weak acid is 3.00. What is the percentage ionisation?
Percentage ionisation = ([H+]/[HA]initial) x 100
The Ka of a weak acid HA is 1.0 x 10^-5 mol dm-3. What is the pH of a 0.10 mol dm-3 solution of HA?
A 0.10 mol dm-3 solution of a weak acid HA has pH = 3.0. The solution is diluted ten-fold with distilled water. What happens to the percentage dissociation of HA?
Dilution shifts a weak acid's equilibrium further towards ionisation.
Which equation represents the correct equilibrium for the dissociation of a weak acid HA?
A weak acid only partially dissociates, so use a reversible arrow.
Which of the following aqueous solutions has the lowest pH?
This acid can release two H+ ions per molecule.
