Chapter 5 Lecture Notes - Chapter 5 Thermochemistry The...

Info icon This preview shows pages 1–18. Sign up to view the full content.

View Full Document Right Arrow Icon
Thermochemistry Chapter 5 Thermochemistry The energy of chemical reactions. How do you keep track of it? Where does it come from?
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Energy The ability to: do work transfer heat. Work: Energy used to cause an object that has mass to move. Heat: Energy used to cause the temperature of an object to rise. We will see that both are due to molecular motion.
Image of page 2
Thermochemistry Potential Energy Energy an object possesses by virtue of its position or chemical composition. More potential E Less P.E. as bike goes down.
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Kinetic Energy Energy an object possesses by virtue of its motion. 1 2 KE = mv 2
Image of page 4
Thermochemistry Units of Energy The SI unit of energy is the joule (J) . An older, non-SI unit is still in widespread use: The calorie (cal) . 1 cal = 4.184 J 1 J = 1  kg m 2 s 2
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Energy accounting Must identify where different types of Energy go. Therefore, must identify the places.
Image of page 6
Thermochemistry System and Surroundings The system includes the molecules we want to study (here, the hydrogen and oxygen molecules). The surroundings are everything else (here, the cylinder and piston).
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Work Energy used to move an object over some distance. w = F d , w = work, F = force d = distance over which the force is exerted.
Image of page 8
Thermochemistry Heat Energy can also be transferred as heat. Heat flows from warmer objects to cooler objects.
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Transfer of Energy a) Add P.E. to a ball by lifting it to the top of the wall
Image of page 10
Thermochemistry Transferal of Energy a) Add P.E. to a ball by lifting it to the top of the wall b) As the ball falls, P.E ------> K. E. (1/2mv 2 )
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Transferal of Energy a) Add P.E. to a ball by lifting it to the Ball hits ground, K.E. =0, but E has to go somewhere. So 1. Ball gets squashed 2. Heat comes out.
Image of page 12
Thermochemistry First Law of Thermodynamics Energy is conserved. In other words, the total energy of the universe is a constant; Δ E System = - Λ E surroundings
Image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Internal Energy The internal energy of a system is the sum of all kinetic and potential energies of all components of the system; we call it E. E internal, Total = E K.E. + E P.E. + E electrons + E nuclei + ........ almost impossible to calculate total internal energy. Instead, we are always looking at change in energy ( Δ E)
Image of page 14
Thermochemistry Internal Energy By definition, the change in internal energy, Δ E , is the final energy of the system minus the initial energy of the system: Δ E = E final E initial Use Fig. 5.5
Image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Thermochemistry Changes in Internal Energy • If Δ E > 0, E final > E initial Therefore, the system absorbed energy from the surroundings. This energy change is called endergonic .
Image of page 16
Thermochemistry Changes in Internal Energy • If Δ E < 0, E final < E initial Therefore, the system released energy to the surroundings.
Image of page 17

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 18
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern