Enthalpy Changes and Hess's Law

This video tutorial by Mr. Anderson covers the enthalpy of reaction, explaining how energy is absorbed or released during chemical reactions. It discusses the concepts of bond energy, endothermic and exothermic reactions, and introduces Hess's Law. The video also explains how to measure enthalpy using a calorimeter and explores the Born-Haber cycle. Finally, it demonstrates the application of Hess's Law in solving enthalpy problems, emphasizing the importance of understanding the sum of reaction parts.

What was the main reason Alfred Nobel invented dynamite?

• To win a Nobel Prize

• To reduce mining costs

• To stabilize nitroglycerin

• To create a more powerful explosive

In an endothermic reaction, how does energy flow?

• From the reaction to the surroundings

• From the surroundings to the reaction

• Energy is neither absorbed nor released

• Energy is created within the reaction

What does a negative value in an enthalpy change indicate?

• The reaction is at equilibrium

• The reaction absorbs energy

• The reaction is exothermic

• The reaction is endothermic

Which tool is used to measure the enthalpy change in a reaction?

• Thermometer

• Spectrometer

• Calorimeter

• Barometer

What is the Born-Haber cycle used for?

• Balancing chemical equations

• Calculating lattice energy

• Determining reaction speed

• Measuring temperature changes

What is the significance of a positive enthalpy change?

• The reaction is endothermic

• The reaction is at equilibrium

• The reaction is exothermic

• The reaction releases energy

According to Hess's Law, what happens if you reverse a reaction?

• The reaction becomes exothermic

• The enthalpy change sign is reversed

• The reaction becomes endothermic

• The enthalpy change remains the same

What is the main principle behind Hess's Law?

• Energy can be created

• Energy can be destroyed

• The total enthalpy change is the sum of individual steps

• The enthalpy change is always positive

How can you algebraically solve for the enthalpy change of a reaction?

• By summing the enthalpy changes of individual steps

• By reversing the reaction

• By using a balance beam

• By measuring the temperature

What happens to the enthalpy change if a reaction is multiplied by a factor?

• The enthalpy change is divided by the factor

• The enthalpy change is multiplied by the factor

• The enthalpy change remains unchanged

• The enthalpy change becomes zero