The Mole, Formulae and Chemical Equations

Syllabus tag: KCSE | Chemistry | Form 3 | Topic 13 The Mole, Formulae and Chemical Equations

Lesson objectives

By the end of this topic, you should be able to:

• Define the mole and relate it to mass, volume and number of particles.
• Calculate empirical and molecular formulae from composition data.
• Write and balance chemical and ionic equations.
• Perform calculations from equations, including concentration and titration.

Summary

The mole is the amount of substance containing 6.0 × 10²³ particles — Avogadro's number. For a solid, moles = mass ÷ molar mass. For a gas, moles = volume ÷ molar gas volume (22.4 dm³ at s.t.p.). For a solution, moles = concentration × volume in dm³. Every calculation converts to moles, uses the equation ratio, then converts back.