Energetics in Chemistry

What is an exothermic reaction?

• A reaction that only releases energy in the form of sound.

• A chemical reaction that absorbs energy in the form of heat or light.

• A reaction that does not involve any energy change.

• A chemical reaction that releases energy in the form of heat or light.

Provide an example of an exothermic reaction and explain why it is classified as such.

• Combustion of methane (CH4) in the presence of oxygen (O2) to produce carbon dioxide (CO2) and water (H2O)

• Photosynthesis of plants

• Boiling water

• Dissolving sugar in water

Define endothermic reaction.

• A chemical reaction that does not involve heat

• A chemical reaction that only occurs at high temperatures

• A chemical reaction that absorbs heat from its surroundings

• A chemical reaction that releases heat to its surroundings

What is enthalpy change?

• The change in color of a substance during a reaction

• Heat energy transferred in a reaction at constant pressure

• The change in volume of a substance during a reaction

• The change in mass of a substance during a reaction

How is enthalpy change represented in a chemical equation?

• H2O

• ΔG

• C6H12O6

• ΔH

Explain the difference between exothermic and endothermic reactions in terms of enthalpy change.

• Exothermic reactions absorb heat energy from the surroundings, resulting in a positive enthalpy change.

• Endothermic reactions release heat energy to the surroundings, resulting in a negative enthalpy change.

• Exothermic reactions do not involve any change in heat energy.

• Exothermic reactions release heat energy to the surroundings, resulting in a negative enthalpy change. Endothermic reactions absorb heat energy from the surroundings, resulting in a positive enthalpy change.

How is enthalpy change measured in a laboratory setting?

• Chromatography

• Titration

• Calorimetry

• Spectroscopy

Discuss the impact of temperature on the enthalpy change of a reaction.

• The impact of temperature on enthalpy change is negligible

• Temperature has no impact on the enthalpy change of a reaction

• Temperature affects the enthalpy change of a reaction by increasing or decreasing it.

• Enthalpy change of a reaction is only affected by pressure, not temperature