Thermochemistry Quiz

What happens to energy during a chemical reaction?

• It is created
• It is destroyed
• It is transformed
• It remains constant

Which of the following best describes an exothermic reaction?

• Absorbs heat from the surroundings
• Releases heat to the surroundings
• No heat exchange occurs
• Increases the temperature of the reactants

In an endothermic reaction, the system:

• Releases energy
• Absorbs energy
• Maintains energy balance
• None of the above

According to the first law of thermodynamics, energy cannot be:

• Created
• Destroyed
• Transformed
• Both a and b

Which of the following is an example of an exothermic reaction?

• Photosynthesis
• Combustion of gasoline
• Dissolving ammonium nitrate in water
• Baking bread

What is the primary factor that distinguishes exothermic from endothermic reactions?

• Change in temperature
• Energy flow
• Type of reactants
• Presence of a catalyst

In a chemical reaction, if the products have lower energy than the reactants, the reaction is:

• Endothermic
• Exothermic
• Isothermal
• Reversible

What does Hess's Law state?

• Energy is conserved in a chemical reaction
• The total enthalpy change is the same regardless of the pathway taken
• All reactions are reversible
• Temperature affects reaction rates

Which of the following is true about enthalpy (H)?

• It is a measure of energy in a system
• It is always negative
• It cannot be measured
• It is independent of pressure

When calculating the change in enthalpy for a reaction, which value is typically used?

• Standard enthalpies of formation
• Molar mass
• Density of reactants
• Volume of products