01 Introduction to Chemistry
02 Matter and the Atomic Structure
03 The Mole Concept, Chemical Formula and Equation
04 The Periodic Table of Elements
05 Chemical Bond
06 Acids, Bases and Salts
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4.3.5 Reaction of Alkali Metals with Water

Alkali Metals React with Water

Group 1 metals react vigorously with water produces alkali and hydrogen gas

Group 1 Metals + Water → Alkali + Hydrogen gas

Common Observation

  1. Lithium, sodium or potassium floats and move around on the surface of the water and then dissolve in the water.
    Conclusion:
    Lithium, sodium and potassium are less dense than water.
  2. Colourless gas is released around the metal. The gas produces a “pop” sound when ignited with a lighted wooden splinter.
    Conclusion:
    The colourless flammable gas is hydrogen.
  3. The solution turns blue when it is tested with universal indicator.
    Conclusion:
    the solution produced is an alkali.

Lithium + Water

2Li + 2H2O → 2LiOH + H2

Observation
Lithium metal moves slowly on the surface of the water with ‘fizzing’ sound.

Sodium + Water

2Na + 2H2O → 2NaOH + H2

Observation
The lump of sodium moves swiftly on the surface of the water with ‘fizzing’ sound

Potassium + Water

2K + 2H2O → 2KOH + H2

Observation
Potassium reacts violently with water, move very fast on the surface of the water and burn with a lilac flame.