Enthalpy Changes and Reaction Types

The video tutorial explains how to interpret a potential energy profile graph for chemical reactions. It covers calculating the potential energy of reactants and products, determining the enthalpy change for forward and backward reactions, and understanding energy absorption and release. The tutorial also distinguishes between endothermic and exothermic reactions based on enthalpy changes.

What does the y-axis represent in the potential energy profile graph?

• Temperature in Celsius

• Time in seconds

• Potential energy in kilojoules per mole

• Reaction progress

How do you determine the potential energy of reactants from the graph?

• By finding the midpoint of the graph

• By calculating the slope of the graph

• By reading the y-axis at the reactants

• By measuring the x-axis at the start

What is the enthalpy change for a forward reaction if the reactants have 30 KJ/mol and the products have 5 KJ/mol?

• -25 KJ/mol

• 25 KJ/mol

• -5 KJ/mol

• 5 KJ/mol

What does a negative enthalpy change indicate about a reaction?

• The reaction is at equilibrium

• Energy is absorbed

• Energy is released

• The reaction is endothermic

If a reaction releases energy, what type of reaction is it?

• Adiabatic

• Endothermic

• Isothermal

• Exothermic

In the backward reaction example, what is the potential energy of the reactants?

• 30 KJ/mol

• 40 KJ/mol

• 50 KJ/mol

• 20 KJ/mol

How is the enthalpy change calculated for a backward reaction?

• Divide initial energy by final energy

• Add initial and final energies

• Multiply initial energy by final energy

• Subtract initial energy from final energy

What does a positive enthalpy change indicate about the backward reaction?

• The reaction is at equilibrium

• The reaction is exothermic

• Energy is absorbed

• Energy is released

If a reaction absorbs energy, what type of reaction is it?

• Endothermic

• Exothermic

• Isothermal

• Adiabatic

What is the enthalpy change for the backward reaction if the products have 30 KJ/mol and the reactants have 40 KJ/mol?

• -10 KJ/mol

• 10 KJ/mol

• 20 KJ/mol

• 0 KJ/mol