Tue June 12, 2012 By: Rajarshi Basu

Give 5 Examples of Light Evolving Reactions.

Expert Reply
Wed June 13, 2012

Light is emitted in many of the chemical reactions but chemical reactions, especially those involving metals give off heat and light energy.

For example:

  1. Li+ + heat energy ?? {Li+ excited state} ? Li+ + Light
  2. Ca2+ + heat energy ? {Ca2+ excited state}? Ca2+ + Light

 3. Magnesium on burning in burning in carbon dioxide produces light:

Mg(s) + CO2(g) ? MgO(s) + C(s)

4. Reaction of sodium with water produces a lot of heat energy and is accompanied with a bright flame.

2Na + 2H2O ?2NaOH + H2

5. Reaction of some organic compounds produces light; this phenomenon is used in chemiluminescent glow sticks.

6. Reaction of potassium with water also produces light and heat.

2K + 2H2O ?2KOH + H2

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