Ca + O2 = CaO

Balanced Chemical Equation – Solution

2Ca + O2 → 2CaO

The coefficients show the number of particles (atoms or molecules), and the indices show the number of atoms that make up the molecule. New substances are formed as a result of the rearrangement of the original atoms. As a result of a chemical reaction, atoms of chemical elements do not disappear anywhere and new ones do not appear, their number remains unchanged – this follows from the law of conservation of mass of substances.

Chemical Reaction Information

Calcium + Dioxygen = Calcium Oxide

This is an oxidation-reduction (redox) reaction. Ca is a reducing agent, O2 is an oxidizing agent.

  • 2 Ca0  4 e  2 CaII (oxidation)
  • 2 O0 + 4 e  2 O-II (reduction)

Reaction Type


Substances that react are called starting materials or reactants. The substances that form as a result are called reaction products.



  • Names: Calcium.
  • Appearance: Silvery-white-to-grey powder.


  • Names: Dioxygen, Oxygen.
  • Appearance: Odourless compressed gas.


CaO – Calcium oxide

  • Other names: Quicklime.
  • Appearance: White to pale yellow/brown powder.
Similar Examples of Equalizing a Chemical Reaction
O2 + Ca → Ca2O3
O2 + Ca → Ca2O2
H2O + O2 + Ca → H2 + Ca(OH)2
O2 + H2 + Ca → Ca(OH)2
O2 + Ca → CaO
O2 + P + Ca → CaPO4
O2 + Ca → Ca2O
O2 + Ca → CaO2
O2 + Ca → Ca8O4

Alexander Stephenson

Candidate of Chemical Sciences, editor-in-chief of Lecturer at several international online schools, member of the jury of chemistry competitions and author of scientific articles.

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