A chemist wants to observe the following reaction:

Question

A chemist wants to observe the following reaction:

2H2 + O2 → 2H2O
The chemist is standing inside a room with oxygen in the air and has a balloon filled with hydrogen. The chemist holds a small flame up to the hydrogen balloon. When the balloon pops, the hydrogen explodes in a ball of fire.
Based on what you know about breaking and forming bonds, explain which part of the reaction is higher in energy (i.e., does it take more energy to break the bonds of the reactants, or is more energy given off when the product bonds are formed?). Defend your answer in three to five sentences

Answer 1

In the given reaction, hydrogen and oxygen molecules initially have bonds that need to be broken in order to form the water molecules. It takes energy to break these bonds, as energy is required to overcome the forces that hold the atoms together in the molecules. This initial input of energy to break the bonds is known as the activation energy. Once the bonds are broken and the products are formed, the energy released from the formation of new bonds is greater than the energy required to break the initial bonds. This excess energy is released as heat and light, leading to the explosion and fire observed in the reaction. Overall, more energy is given off when the product bonds are formed compared to the energy required to break the bonds of the reactants.