When hydrogen gas (H2) reacts with oxygen gas (O2), a highly exothermic chemical reaction occurs, resulting in the formation of water (H2O). This reaction is commonly known as the combustion or burning of hydrogen. The reaction can be represented by the following equation:
2H2 + O2 → 2H2O
In this reaction, two molecules of hydrogen combine with one molecule of oxygen to produce two molecules of water. The reaction is highly exothermic, releasing a significant amount of heat energy.
When hydrogen reacts with oxygen, the reaction is highly explosive, especially in the presence of a spark or flame. The reaction produces a vigorous flame and may generate a loud popping sound or even an explosion, depending on the conditions and the amount of hydrogen and oxygen present.
During the reaction, the flame is pale blue and very hot. The heat released by the reaction excites the electrons in the gas, resulting in the emission of light. However, the flame itself is nearly invisible to the naked eye, which is why it may appear colorless.
In terms of observation, when hydrogen reacts with oxygen, you may see a flame and feel the intense heat generated by the reaction. If the reaction is carried out in a controlled environment, you will notice the formation of water vapor as a byproduct, which may condense into liquid water droplets if the conditions allow.