Acids and bases

• What is a Bronsted-Lowry acid?

  A substance that can donate a proton
• What is a Bronsted-Lowry base?

  A substance that can accept a proton
• What happens when HCl reacts with water?

  It forms H3O+ and Cl- ions
• What is the relationship between acids and their conjugate bases?

  • Each acid is linked to a conjugate base
  • Conjugate base forms after the acid donates a proton
• What is the formula for calculating pH?

  pH = - log [H+]
• How do strong acids behave in solution?

  They completely dissociate in solution
• What is the pH of a 0.1 mol dm-3 HCl solution?

  pH = 1.00
• How do you find [H+] from pH?

  [H+] = 10^-ph
• What is the concentration of HCl with a pH of 1.35?

  [H+] = 0.045 mol dm-3
• What is the ionic product for water (Kw)?

  • Kw = [H+][OH-]
  • At 25°C, Kw = 1 x 10^-14 mol2dm-6
• Why is pure water neutral?

  [H+]=[OH-] in pure water
• How do you calculate [H+] in neutral water using Kw?

  [H+] = √Kw
• What is the pH of pure water at 25°C?

  pH = 7
• How does temperature affect the pH of pure water?

  Higher temperature lowers pH
• What is the pH of water at 50°C with Kw = 5.476 x 10^-14

  pH = 6.6
• How do strong bases behave in solution?

  They completely dissociate into ions
• How do you calculate pH from [OH-] for strong bases?

  Use Kw to find [H+]
• What is the pH of 0.1 mol dm-3 NaOH?

  pH = 13.00
• What is the dissociation expression for weak acids?

  • HA + H2O ⇌ H3O+ + A-
  • Ka = [H+][A-]/[HA]
• What is the Ka for ethanoic acid?

  1.7 x 10^-5 mol dm-3
• What does a larger Ka indicate?

  Stronger acid
• What is the pH of 0.01 mol dm-3 ethanoic acid?

  pH = 3.38
• How do you find [H+] from pH for weak acids?

  [H+] = √(Ka × [HA]initial)
• What is the concentration of propanoic acid with a pH of 3.52?

  [CH3CH2CO2H] = 6.75 x 10^-3 mol dm^-3
• What is the relationship between pKa and Ka?

  • pKa = -log Ka
  • Ka = 10^-pka
• What are the steps for calculating pH in neutralization reactions?

  1. Calculate moles of acid and base
  2. Determine which is in excess
  3. Calculate new concentration of excess ions
  4. Use pH formula to find pH
• How do you calculate pH for strong acid and strong base neutralizations?

  Use excess moles to find [H+]
• What is the pH of the mixture from 45cm3 of 1.0 mol dm-3 HCl and 30cm3 of 0.65 mol dm-3 NaOH?

  pH = 0.47
• What is the pH of the mixture from 15cm3 of 0.5 mol dm-3 HCl and 35cm3 of 0.55 mol dm-3 NaOH?

  pH = 13.37
• What is the pH of the mixture from 15cm3 of 0.5 mol dm-3 HCl and 35cm3 of 0.45 mol dm-3 Ba(OH)2?

  pH = 13.68
• What is the pH of the mixture from 35cm3 of 0.5 mol dm-3 H2SO4 and 30cm3 of 0.55 mol dm-3 NaOH?


  pH = 0.55
• What is the difference between strong diprotic acids and bases in neutralization calculations?

  • Strong diprotic acids release two protons
  • Strong diprotic bases release two hydroxide ions
• What is the formula for calculating moles of a substance?

  Moles = concentration x volume
• What is the pH of a solution with $[H^+] =$$2.08 \times 10^{-14} \text{ mol dm}^{-3}$?


  13.68
• How do you calculate the concentration of $[OH^-]$ in a mixture?


  $[OH^-] =$$\frac{moles \, excess \, OH^-}{total \, volume \, (dm^3)}$
• What is the relationship between moles of $H^+$ and $OH^-$ in a neutralization reaction?


  They react in a 1:1 ratio to form water
• How do you calculate the moles of $H_2SO_4$ in a reaction?


  Moles = concentration x volume
• What is the pH of a solution with $[H^+] =$$0.28 \text{ mol dm}^{-3}$?


  0.55
• What are the steps to calculate the pH of a weak acid and strong base neutralization?

  1. Calculate moles of acid and base.
  2. Determine which is in excess.
  3. Calculate new concentration of excess acid or base.
  4. Use $pH =$$-\log[H^+]$ or $pOH =$$-\log[OH^-]$ as needed.
• What is the formula for calculating the pH of a weak acid at half equivalence?

  pH = pKa