Chemical Reactions and Energy Changes

This video tutorial covers exothermic and endothermic processes, bond energy calculations, and energy diagrams. It explains the law of conservation of energy, defines system and surroundings, and provides examples of exothermic and endothermic reactions. The tutorial also demonstrates how to calculate bond energy to determine if a reaction is exothermic or endothermic, and illustrates energy changes using energy diagrams. Practice questions are included to reinforce understanding.

What happens to the temperature of the surroundings during an exothermic reaction?

• It increases.

• It decreases.

• It remains constant.

• It fluctuates.

Which of the following is an example of an endothermic process?

• Melting of ice

• Freezing of water

• Combustion of methane

• Rusting of iron

In bond energy calculations, what does a negative change in enthalpy indicate?

• The reaction does not occur.

• The reaction is endothermic.

• The reaction is exothermic.

• The reaction is at equilibrium.

What is the bond energy of an oxygen double bond oxygen?

• 631 KJ per mole

• 436 KJ per mole

• 498 KJ per mole

• 464 KJ per mole

In an energy diagram, what does the peak represent?

• The initial energy state

• The equilibrium state

• The final energy state

• The transition state

What is the role of a catalyst in a chemical reaction?

• It increases the potential energy of the reactants.

• It decreases the potential energy of the products.

• It changes the enthalpy change of the reaction.

• It lowers the activation energy.

In an endothermic reaction, what happens to the enthalpy of the system?

• It decreases.

• It remains constant.

• It fluctuates.

• It increases.

Which of the following reactions is exothermic?

• Photosynthesis

• Baking bread

• Combustion of methane

• Electrolysis of water

What is the enthalpy change when 2 H2 + Cl2 gives 2 HCl?

• -1883 KJ per mole

• -183 KJ per mole

• +183 KJ per mole

• +1883 KJ per mole

In an energy diagram, what does a negative Delta H indicate?

• The reaction does not occur.

• The reaction is endothermic.

• The reaction is at equilibrium.

• The reaction is exothermic.