Reaction between hydrogen and oxygen
When hydrogen and oxygen molecules collide, they form a covalent bond to form a water molecule. The electrons from the hydrogen atoms are shared with the oxygen atoms to form the polar covalent bonds that make up a water molecule. The water molecule then separates from the two reactants and forms its own molecule.
Hydrogen and oxygen react to form water. The chemical equation for this reaction is:
2H2 + O2 -> 2H2O
Reaction between hydrogen and chlorine
In the presence of an electric spark, or a source of heat, the hydrogen and chlorine molecules combine to form hydrochloric acid (HCl). The reaction is exothermic, meaning that energy is released in the form of heat. The reaction is also quite explosive and can be hazardous if not handled properly.
Hydrogen and chlorine form hydrochloric acid when they react. The reaction is represented by the following equation:
2H2 + Cl2 → 2HCl