5.3 Acids, Bases, Buffers

• What is a Brønsted acid?

  A species that can donate a proton
• How does hydrogen chloride (HCl) act as a Brønsted acid?

  It loses a proton to form H and Cl ions
• What is a Brønsted base?

  A species that can accept a proton
• How does a hydroxide ion (OH-) act as a Brønsted base?

  It accepts a proton to form water
• What occurs in an equilibrium reaction?

  Products form at the same rate as reactants
• What species are present when ethanoic acid reaches equilibrium?

  CH3COOH, H2O, CH3COO-, and H3O+
• What is a conjugate acid-base pair?

  Two species differing by one proton
• How are acids classified based on proton donation?

  By the number of protons they can donate
• What are monobasic acids?

  Acids with one ionizable hydrogen atom
• What happens when HCl reacts with NaOH?

  One hydrogen is replaced by sodium
• What are dibasic acids?

  Acids with two ionizable hydrogen atoms
• How does H2SO4 ionize in reactions?

  In two steps, releasing two protons
• What are tribasic acids?

  Acids with three ionizable hydrogen atoms
• What occurs when H3PO4 reacts with NaOH?

  Three hydrogens are replaced by sodium
• What do metals, alkalis, and carbonates form when reacting with acids?

  Salts, water, and gases
• What is the typical reaction of a metal with an acid?

  Acid + metal → salt + hydrogen
• What is the ionic equation for the reaction of HCl and Zn?

  2H+(aq) + Zn(s) → Zn2+(aq) + H2(g)
• What do acids and metal oxides produce when they react?

  Salt and water
• What is the reaction of an acid with a metal carbonate?

  Acid + metal carbonate → salt + water + CO2
• What happens when HNO3 reacts with CuCO3?

  Produces Cu(NO3)2, water, and CO2
• What is the general reaction of acids with alkalis?

  Acid + alkali → salt + water
• What is the definition of a weak acid?

  An acid that partially dissociates in solution

  
• What does the acid dissociation constant (Ka) indicate?

  The extent of dissociation of a weak acid

  
• What is the typical value of Ka for weak acids?

  Very small values, e.g., 1.74 x 10^-5

  
• What is the relationship between Ka and acid strength?

  Higher Ka means stronger acid

  
• What is pKa?

  The negative log of Ka
• How is pH defined?

  pH = -log[H+]
• How can [H+] be calculated from pH?

  [H+] = 10^(-pH)

  
• What does the pH scale represent?

  A logarithmic scale of hydrogen ion concentration

  
• What is the ionic product of water (Kw)?

  The product of [H+] and [OH-] concentrations

  
• What is the value of Kw at 25°C?

  1 x 10^-14 mol^2/dm^6
• How does the concentration of H+ relate to OH- in pure water?

  [H+] = [OH-] in pure water

  
• What is the characteristic of strong acids in solution?

  They are completely ionized in solution
• How is the concentration of hydrogen ions related to strong acids?

  [H+] equals the concentration of the acid

  
• What is the pH of 0.01 mol/dm^3 hydrochloric acid?

  pH = 2.00
• What is the relationship between strong bases and ionization?

  Strong bases are completely ionized in solution
• How is the concentration of hydroxide ions related to strong bases?

  [OH-] equals the concentration of the base

  
• What is the characteristic of strong acids in solution?

  They are completely ionised in solution
• How can the ionisation of a strong acid be represented?

  HA (aq) → H⁺ (aq) + A^- (aq)
• What is the relationship between hydrogen ion concentration and acid concentration for strong acids?

  The concentration of H⁺ equals the concentration of HA