5.3 The energy change of reactions

• Exothermic reactions absorb energy from the surroundings.

  False
• What is the temperature change observed in the surroundings during an endothermic reaction?

  Decreases
• How is energy transferred to the surroundings in an exothermic reaction?

  As heat
• What do energy diagrams visually represent in exothermic and endothermic reactions?

  Energy changes
• During an exothermic reaction, energy is released to the surroundings, causing the temperature to increase
• In endothermic reactions, energy is absorbed from the surroundings, causing the temperature to decrease.

  True
• Changes in the physical state of reactants or products can affect the energy change of a reaction.


  True
• Increasing the pressure affects the energy change of reactions, especially for gases.


  True
• Endothermic reactions absorb energy from the surroundings, causing the temperature to decrease
• Match the reaction type with its energy and temperature changes:

  Exothermic ↔️ Energy released, temperature increases

  Endothermic ↔️ Energy absorbed, temperature decreases
• Match the reaction type with its energy and temperature changes:

  Exothermic ↔️ Energy released, temperature increases

  Endothermic ↔️ Energy absorbed, temperature decreases
• In an exothermic reaction, the reactants have higher potential energy than the products


  True
• In an endothermic reaction energy diagram, the movement from reactants to products is upward
• The enthalpy change (ΔH) is positive for endothermic reactions

  True
• What happens to the temperature of the surroundings in an exothermic reaction?

  Increases
• In endothermic reactions, energy is absorbed from the surroundings in the form of heat
• In endothermic reactions, energy is absorbed from the surroundings as heat
• The direction of energy flow in an endothermic reaction is from the surroundings to the system.


  True
• What does a downward arrow in an energy diagram for an exothermic reaction indicate?

  Release of energy
• In exothermic reactions, the reactants have a higher potential energy than the products.


  True
• In endothermic reactions, what is the energy relationship between reactants and products?

  Products have higher energy
• When chemical bonds are broken, energy is absorbed, making the process endothermic
• Which phase change releases more energy: water vapor condensing to liquid water or liquid water freezing to solid ice?

  Water vapor condensing
• Match the factor affecting energy change with its effect:

  Bond breaking ↔️ Absorbs energy (endothermic)

  Bond formation ↔️ Releases energy (exothermic)

  Increased temperature ↔️ Generally increases energy change
• In exothermic reactions, energy is released from the reactants, reducing the potential energy of the system.


  True
• In exothermic reactions, energy is released from the reactants to the surroundings
• In endothermic reactions, energy is absorbed from the surroundings to increase the potential energy of the system
• In an exothermic reaction energy diagram, the movement from reactants to products is downward
• Match the factor affecting energy change with its effect:

  Bond breaking ↔️ Absorbs energy (endothermic)

  Bond formation ↔️ Releases energy (exothermic)

  State changes ↔️ Increases or decreases energy change
• Match the reaction type with a real-life example:

  Exothermic ↔️ Combustion

  Endothermic ↔️ Photosynthesis
• What happens to the potential energy of the system in an exothermic reaction?

  Decreases
• In exothermic reactions, the potential energy of the system decreases
• The temperature of the surroundings increases during an endothermic reaction.

  False
• What happens to energy when chemical bonds are formed in a reaction?

  Energy is released
• Increasing the temperature generally increases the energy change of a reaction because it provides more energy
• What is the primary form of energy released in exothermic reactions?

  Heat
• What happens to the temperature of the surroundings in an endothermic reaction?

  It decreases
• Endothermic reactions increase the temperature of the surroundings

  False
• In an endothermic reaction, the products have lower potential energy than the reactants

  False
• The enthalpy change (ΔH) is negative for exothermic reactions, indicating energy is released