SPM Chemistry Form 4 Notes – Acids and Bases (Part 1)

by BerryBerryTeacher

in Berry Reference (Notes)

Acids and bases (alkali) are something which most Berry Readers will imagine to be only available in labs of mad scientists, due to perception seen in cartoons or science-fiction movies. However, in reality, acids are less ‘glamourous’ and they appear in everyday food such as lemon (citric acid) and vinegar (acetic acid) and most others that taste sour. Similarly, bases although less commonly embedded in a student’s mind, but are also equally commonly found. So this Part 1 from the new series of notes for SPM Chemistry Form 4 on Acids and Bases from Berry Berry Easy will be on the introduction of acids and bases/alkalis to set the tone for the subsequent notes.

[Tips: Try to have a look at all possible solutions at home and see if you can identify which are acids and which are bases. Then proceed to compare your findings with information obtained from the Internet. This is a simple yet important exercise to allow you to fully understand what constitutes acids or alkalis.]

SPM Chemistry Form 4 Notes – Acids and Bases (Part 1)


  • An acid is a chemical substance which ionises in water to produce hydrogen ions, H+ / hydroxonium ions, H3O+.
  • H+(aq) + H2O(l) –> H3O+(aq)
  • Example: HCl(g) + H2O(l) –> H3O+(aq) + Cl -(aq)
Acid Acid name Ions
HCl Hydrochloric acid H+, Cl -
HNO3 Nitric acid H+, NO3-
H2SO4 Sulphuric acid H+, SO42-
CH3COOH Ethanoic acid H+, CH3COO -
  • Monoprotic acid = acid can produce only one hydrogen ion per molecule in water. (Example: HCl)
  • Diprotic acid = acid can produce two hydrogen ions per molecule in water. (Example: H2SO4)
  • Triprotic acid = acid can produce three hydrogen ions per molecule in water. (Example: H3PO4)
Sodium hydroxide

Sodium hydroxide

Bases / Alkalis

  • A base is a chemical substance which reacts with an acid to produce a salt and water only.
  • Base(s) + acid(aq) –> salt + water (l).
  • Example: NaOH(s) + HCl(aq) –> NaCl(aq) + H2O(l)
Base Formula Solubility in water Ions in the aqueous solution
Copper(II) oxide CuO Insoluble base -
Lead(II) oxide PbO Insoluble base -
Magnesium oxide MgO Insoluble base -
Zinc hydroxide Zn(OH)2 Insoluble base -
Aluminium hydroxide Al(OH)3 Insoluble base -
Sodium oxide Na2O Soluble base (alkali) Na+, O2-
Calcium oxide CaO Soluble base (alkali) Ca2+, O2-
Sodium hydroxide NaOH Soluble base (alkali) Na+, OH-
Potassium hydroxide KOH Soluble base (alkali) K+, OH-
Barium hydroxide Ba(OH)2 Soluble base (alkali) Ba2+, OH-

This ends Part 1 of the notes for SPM Chemistry Form 4 on Acids and Bases from Berry Berry Easy. In the next part in the series, you’ll learn about the uses of acid and bases in our daily life. So do stay tuned and log on to this site in the future.

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