7.2 Energy Changes

• In an exothermic reaction, the energy stored in the products is higher than in the reactants.

  False
• Match the type of reaction with its example:

  Exothermic ↔️ Burning fuels

  Endothermic ↔️ Melting ice
• Arrange the following energy changes in an endothermic reaction in order:

  1️⃣ Reactants have lower energy

  2️⃣ Energy is absorbed from surroundings

  3️⃣ Products have higher energy

  4️⃣ Temperature decreases
• Endothermic reactions absorb energy from the surroundings, usually in the form of heat
• Exothermic reactions are chemical reactions that release energy, usually in the form of heat
• Exothermic reactions result in a decrease in the temperature of the surroundings.

  False
• An example of an exothermic reaction is the combustion of methane
• Endothermic reactions increase the temperature of the surroundings.

  False
• High activation energy leads to a fast reaction rate.

  False
• A low activation energy results in a fast reaction rate.

  True
• Endothermic reactions absorb energy from the surroundings, usually in the form of heat
• Exothermic reactions release energy, while endothermic reactions absorb energy.
• What happens to the temperature of the surroundings in an endothermic reaction?

  It decreases
• Name an example of an endothermic reaction.

  Melting ice
• Exothermic reactions release energy in the form of heat, causing the temperature to increase.


  True
• Arrange the following characteristics to summarize the differences between exothermic and endothermic reactions:

  1️⃣ Energy released vs. absorbed

  2️⃣ Temperature increases vs. decreases

  3️⃣ Products have lower vs. higher energy
• Match the component of an exothermic reaction with its energy level:

  Reactants ↔️ Higher

  Products ↔️ Lower
• Melting ice is an example of an endothermic reaction.


  True
• What is activation energy?

  Minimum energy to start a reaction
• What happens to the reaction rate when the activation energy is high?

  It becomes slow
• What do energy diagrams show about chemical reactions?

  Energy changes
• What is the energy change in an endothermic reaction?

  Energy is absorbed
• How do catalysts affect the activation energy of a reaction?

  They lower it
• What is an exothermic reaction?

  Releases energy to surroundings
• Give an example of an exothermic reaction.

  Burning fuels
• Exothermic reactions cause the temperature of the surroundings to decrease.

  False
• Match the type of reaction with an example:

  Exothermic ↔️ Burning fuels

  Endothermic ↔️ Melting ice
• Endothermic reactions absorb energy from the surroundings, usually in the form of heat
• Exothermic reactions release energy, primarily in the form of heat
• In an endothermic reaction, the energy stored in the reactants is lower than the energy stored in the products
• Arrange the following characteristics to summarize the key aspects of endothermic reactions:

  1️⃣ Energy absorbed

  2️⃣ Temperature decreases

  3️⃣ Products have higher energy
• A catalyst lowers the activation energy by providing an alternative pathway
• Increasing the temperature raises the kinetic energy
• Lowering the activation energy barrier allows the reaction to proceed more rapidly.


  True
• Exothermic reactions release energy, causing the temperature to increase.

  True
• The minimum energy required for a reaction to start is called the activation energy
• What does a catalyst do to the activation energy?

  Lowers it
• In an exothermic reaction, the energy level of the products is lower than the energy level of the reactants
• Endothermic reactions cause the temperature of the surroundings to decrease.


  True