Energy in chemical changes:

Energy in chemical changes:

• A. Energy is important as it affects how atoms interact and change during chemical reactions.
• B. Energy is always released
• C. Energy only affects physical changes
• D. Energy is not involved in chemical changes

Answer: (A)

Energy plays a central role in chemical changes because breaking bonds requires energy and forming new bonds releases energy. The way energy flows in a reaction determines whether it is exothermic or endothermic and how readily the reaction proceeds, since the activation energy sets the barrier that must be overcome for the atoms to rearrange. Catalysts can lower this barrier, speeding up the process without changing the overall energy change. Some reactions do release energy, but others absorb energy from the surroundings, so energy is not always released. Energy is also involved in chemical changes, not just physical ones.

Energy plays a central role in chemical changes because breaking bonds requires energy and forming new bonds releases energy. The way energy flows in a reaction determines whether it is exothermic or endothermic and how readily the reaction proceeds, since the activation energy sets the barrier that must be overcome for the atoms to rearrange. Catalysts can lower this barrier, speeding up the process without changing the overall energy change. Some reactions do release energy, but others absorb energy from the surroundings, so energy is not always released. Energy is also involved in chemical changes, not just physical ones.