Acids, bases and neutralisation

Question 1

What are acids?

Answer 1

• Acids are proton donors as they release hydrogen ions when mixed with water.
  e.g:
  H2SO4 + H2O = 2H(+) + SO4(2-)
• Strong acids completely dissociates by releasing all Hydrogen atoms in aqueous solution:
  HCl -> H(+) + Cl(-)
• Weak acids partially dissociates as only small proportion of hydrogen atoms are released as ions in aq. solutions:
  CH3COOH <=> H(+) + CH3COOH(-)
  <=> equilibrium sign indicates that forward reaction is incomplete.

Question 2

Bases and alkalis

Answer 2

• Bases neutralise acid to form salts.
• Alkali is a base that dissolves in water and releases Hydroxide ions (OH-) in solution:
  NaOH -> Na(+) + OH(-)

Question 3

Neutralisation

Answer 3

• General formula of neutralisation reaction is:
  Acid + Base -> Salt + Water
  Ionic reaction:
  H(+) + OH(-) -> H2O

Question 4

Products of neutralisation

Answer 4

• Acid + METAL -> salt + hydrogen
• Acid + metal OXIDE* -> salt + water
• Acid + metal CARBONATE** -> salt + water = carbon dioxide
• reaction of metal hydroxide is the same as metal oxide ** reaction of metal hydrogen carbonate is the same as metal carbonate

Question 5

Charges of some ions

Answer 5

NH4(+)

NO3(-), HCO3(-), Ethanoate: CH3COO(-)

SO4(2-), CO3(2-)

PO4(3-)

Question 6

Partial and complete neutralisation reactions of carbonic acid w/ sodium hydroxide

Answer 6

NaOH + H2CO3 -> NaHCO3 + H2O

2NaOH + H2CO3 -> Na2CO3 + 2H2O

Question 7

Why is sodium hydrogencarbonate called an acid salt?

Answer 7

One hydrogen atom has been replaced by a metal ion. The other hydrogen atom can still behave as an acid.