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For more information, please see full course syllabus of Chemistry
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Lecture Comments (7)

0 answers

Post by Robby Carrera on February 28, 2014

AWSOME VOICE! Great way of explaining things!

1 answer

Last reply by: Zachary McCoy
Fri Jan 3, 2014 10:11 PM

Post by Claudia Espinoza on October 30, 2013

Where are you all getting the Delta H numbers from? Is there a table?

0 answers

Post by Shahram Ahmadi N. Emran on July 24, 2013

For the lecture portion "Enthalpy of Formation: Carbon Dioxide" I found following the white board a little confusing. I thought that the equation:

[CS2(l)+ 3O2(g)= CO2(g)+ 2SO2(g)=> -1076]

was being added to the total. However after going back and following you from the beginning it was clear that this equation was not being added but was only written down to show the original equation before it was reversed. In the future please make a note of whats being added. Besides that I should thank you for being best chemistry teacher I've had yet.

I am having a lot of trouble understanding Hess' Law in my Chemistry II class. While the tutorial was a little helpful, it would help even more if you could tell me where I could find more examples.

1 answer

Last reply by: Zachary McCoy
Fri Jan 3, 2014 10:22 PM

Post by Lindsey Person on June 4, 2010

I am having a lot of trouble understanding Hess' Law in my Chemistry II class. While the tutorial was a little helpful, it would help even more if you could tell me where I could find more examples.

0 answers

Post by Elliott Beltran on December 17, 2009

For the lecture portion "Enthalpy of Formation: Carbon Dioxide" I found following the white board a little confusing. I thought that the equation:

[CS2(l)+ 3O2(g)= CO2(g)+ 2SO2(g)=> -1076]

was being added to the total. However after going back and following you from the beginning it was clear that this equation was not being added but was only written down to show the original equation before it was reversed. In the future please make a note of whats being added. Besides that I should thank you for being best chemistry teacher I've had yet.

Energy in Chemical Reactions

  • The forms of energy are kinetic – from motion – and potential – from position or chemical composition

  • Learn units of energy: SI – Joule; the Calorie in nutrition; Cal = 1000cal = 4.18kJ

  • Energy is conserved in changes: not created or destroyed – First Law of Thermodynamics.

  • Master definition of heat capacity, and how to measure it.

  • Enthalpy is heat energy change at constant pressure

  • The calorimeter useful for determining enthalpy changes of chemical and physical changes, including changes of phase

  • Exothermic means heat energy leaves the system to surroundings (feels hot)

  • Endothermic means heat energy enters the system from surroundings (feels cold)

  • Hess’s Law – a First Law statement – treat enthalpy changes by algebra

  • Learn definition of Standard Enthalpy of Formation, DH0

  • Do examples on using Standard Enthalpies of Formation to calculate enthalpy changes in reactions etc.

Energy in Chemical Reactions

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Forms of Energy 1:30
    • Potential Energy and Kinetic Energy
    • Example: Potential
    • Example: Kinetic
  • Units of Energy 5:20
    • Example: Kinetic Energy, Joules
    • Calorie
  • Conservation of Energy 11:41
    • First Law of Thermodynamics
  • Heat Capacity and Measurement 17:10
    • Heat Capacity
    • Calorimeter
    • Examples: Elements and Compounds
  • Enthalpy 25:40
  • Enthalpy Changes in Physical/Chemical Processes 31:25
    • Exothermic
    • Endothermic
    • Example: Water
    • Reversing a Process
    • Example: Hydrogen + Oxygen
  • Hess's Law 42:38
    • Example: Hydrogen + Oxygen
  • Enthalpy of Formation 47:05
    • Example: Hydrogen + Oxygen
  • Enthalpy of Formation: Carbon Disulfide 51:13
  • Additional Example 1