Themodynamics
Energy <ul><li>the ability to do work </li></ul><ul><li>Kinetic  – energy due to movement </li></ul><ul><li>Potential  – s...
First Law of Thermodynamics <ul><li>The total amount of energy in the universe is constant. </li></ul><ul><li>Energy canno...
H + H + H + H + H + - - - - -
Bond Energies <ul><li>Measured in kJ / mol  (kilojoules per mole) </li></ul><ul><li>Double bonds require more energy to br...
Bond Energies <ul><li>exothermic   reactions  – energy released </li></ul><ul><li>endothermic reactions  – energy absorbed...
Potential Energy Diagram EXOTHERMIC REACTION Why is that little hill labeled, Ac?  Ac = activation energy. This is the ene...
Video Clips <ul><li>Hydrogen Explosion </li></ul><ul><li>http://www.youtube.com/watch?v=NYC23ANpEds </li></ul><ul><li>Acti...
Exothermic Reaction
<ul><li>Activation energy is the amount of energy necessary to push the reactants over an energy barrier. </li></ul><ul><u...
Potential Energy Diagram
Second Law of Thermodynamics <ul><li>The universe is becoming more disordered. </li></ul><ul><li>entropy  – a measure of r...
<ul><li>In most energy transformations, energy are converted to heat. </li></ul><ul><ul><li>Automobiles convert only 25% o...
<ul><li>Spontaneous processes  are those that can occur without outside help. </li></ul><ul><ul><li>The processes can be h...
Gibbs Free Energy <ul><li>Energy that can do work </li></ul><ul><ul><li>Heat is “useless” as it dissipates </li></ul></ul>...
Gibbs Free Energy <ul><li>Exergonic reaction  – spontaneous, -   G </li></ul><ul><li>Endergonic reaction  – not spontaneo...
 G 20 240 140 20 140 240 Δ G = G final  – G initial Please determine the activation energy and  Δ G
Equilibrium Equilibrium reactions convert back and forth with minimal energy. For equilibrium reactions:   G = 0
 
 
Adenosine Triphosphate <ul><li>ATP is the primary free energy source for cells </li></ul><ul><li>ATP ADP + P i </li></ul><...
Phosphorylation <ul><li>ATP hydrolysis does not occur on its own. </li></ul><ul><li>Often, the energy is focused through  ...
 
Redox Reactions <ul><li>reactions involving electron transfer </li></ul>
Redox Reactions <ul><li>Reduction  – chemical reaction where an atom gains electrons </li></ul><ul><li>Oxidation  – chemic...
Redox Reactions <ul><li>Reducing Agent  – substance that LOSES electrons; it causes the other substance to be reduced </li...
Redox in the Cell <ul><li>Many metabolic processes consist of chains of redox reactions. </li></ul>A - A B - B C - C D D -
Upcoming SlideShare
Loading in...5
×

Ppt 9 thermochemistry

297

Published on

Published in: Technology, Economy & Finance
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
297
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • Q: In a test tube, why to chemical reactions occur? - likely have heard of two major forms of energy Q: Which is it for chemical reactions? Q: Where is the energy stored for chemical reactions?
  • Q: What other “law” is that similar to? - law of constant mass
  • Q: How much energy does a bond hold? Q: What would be a good way to test that out? - describe the experiment that was done 1) Difficult to look at one molecule  easier for a mole of molecules 2) Zap them with energy 3) Determine how much energy was used
  • Q: Given single and double bonds, which do you suppose requires more energy to break?
  • - we have reactions that release energy and form energy (exothermic and endothermic) Q: How does that work?
  • - energy of chemical reactions can be visualized in a graphical representation 1) x-axis represents progress of the reaction 2) y-axis represents energy of the components -need to indicate energy of the reactants and products Q: Given this difference between reactants and products, what type of reaction is depicted here?
  • Q: What is the purpose of metabolism? - to utilise the energy it produces
  • Q: But we’re continually losing heat... is the universe going to break down and collapse to heat?
  • - energy of chemical reactions can be visualized in a graphical representation 1) x-axis represents progress of the reaction 2) y-axis represents energy of the components -need to indicate energy of the reactants and products Q: Given this difference between reactants and products, what type of reaction is depicted here?
  • Q: How much work energy is available in a reaction in equilibrium? - 0
  • Take a look at the triphosphate. Q: What is the overwhelming charge? - negative Q: Why is this unstable? - likes repel
  • Q: What type of reaction is this? - hydrolysis - catabolism
  • Q: What happens to the energy? - it needs to be focused
  • Q: What reaction do you know of that would be classified as redox? - NaCl
  • - redox is the condensation of the two terms reduction and oxidation - clearly, these reactions are coupled (can’t have one without the other)
  • Ppt 9 thermochemistry

    1. 1. Themodynamics
    2. 2. Energy <ul><li>the ability to do work </li></ul><ul><li>Kinetic – energy due to movement </li></ul><ul><li>Potential – stored energy </li></ul>Chemical potential energy is stored up in the bonds of a molecule.
    3. 3. First Law of Thermodynamics <ul><li>The total amount of energy in the universe is constant. </li></ul><ul><li>Energy cannot be created or destroyed. </li></ul>
    4. 4. H + H + H + H + H + - - - - -
    5. 5. Bond Energies <ul><li>Measured in kJ / mol (kilojoules per mole) </li></ul><ul><li>Double bonds require more energy to break than single bonds </li></ul><ul><li>The greater the bond energy, the more stable the bond. </li></ul>Bond Type Average Bond Energy (kJ/mol) H-H 436 C-H 411 O-H 459 N-H 391 C-C 346 C-O 359 C=O 799 O=O 494
    6. 6. Bond Energies <ul><li>exothermic reactions – energy released </li></ul><ul><li>endothermic reactions – energy absorbed </li></ul><ul><li>energy is required to break bonds </li></ul><ul><li>energy is released to form bonds </li></ul>
    7. 7. Potential Energy Diagram EXOTHERMIC REACTION Why is that little hill labeled, Ac? Ac = activation energy. This is the energy that reactants must absorb in order to form products.
    8. 8. Video Clips <ul><li>Hydrogen Explosion </li></ul><ul><li>http://www.youtube.com/watch?v=NYC23ANpEds </li></ul><ul><li>Activation Energy Example </li></ul><ul><li>http://www.youtube.com/watch?v=VbIaK6PLrRM&NR=1 </li></ul><ul><li>Activation Energy Song </li></ul><ul><li>http://www.youtube.com/watch?v=XgiCn1IpvzM </li></ul>
    9. 9. Exothermic Reaction
    10. 10. <ul><li>Activation energy is the amount of energy necessary to push the reactants over an energy barrier. </li></ul><ul><ul><li>The difference between free energy of the products and the free energy of the reactants is the delta G. </li></ul></ul>Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 6.12
    11. 11. Potential Energy Diagram
    12. 12. Second Law of Thermodynamics <ul><li>The universe is becoming more disordered. </li></ul><ul><li>entropy – a measure of randomness / disorder </li></ul><ul><ul><li>greater entropy = greater disorder </li></ul></ul><ul><li>metabolise glucose into CO 2 and H 2 O </li></ul><ul><li>C 6 H 12 O 6 + O 2  CO 2 + H 2 O + energy </li></ul>
    13. 13. <ul><li>In most energy transformations, energy are converted to heat. </li></ul><ul><ul><li>Automobiles convert only 25% of the energy in gasoline into motion; the rest is lost as heat. </li></ul></ul><ul><ul><li>Living cells unavoidably convert organized forms of energy to heat. </li></ul></ul><ul><li>Heat is energy in its most random state. </li></ul><ul><li>Combining the two laws, the quantity of energy is constant, but the quality is not. </li></ul>
    14. 14. <ul><li>Spontaneous processes are those that can occur without outside help. </li></ul><ul><ul><li>The processes can be harnessed to perform work. </li></ul></ul><ul><li>Nonspontaneous processes are those that can only occur if energy is added to a system. </li></ul>
    15. 15. Gibbs Free Energy <ul><li>Energy that can do work </li></ul><ul><ul><li>Heat is “useless” as it dissipates </li></ul></ul><ul><li> G = G final – G initial </li></ul><ul><li>For a system to be spontaneous, the system must either give up energy (decrease in H-enthalpy), give up order (decrease in S-entropy), or both. </li></ul><ul><ul><li>Delta G must be negative. </li></ul></ul><ul><ul><li>The greater the decrease in free energy, the greater the maximum amount of work that a spontaneous process can perform. </li></ul></ul><ul><li> G is negative for spontaneous reactions (the rxn moves forward) </li></ul><ul><li> G is positive for reactions that require energy (rxn moves in the reverse direction) </li></ul>
    16. 16. Gibbs Free Energy <ul><li>Exergonic reaction – spontaneous, -  G </li></ul><ul><li>Endergonic reaction – not spontaneous, +  G </li></ul><ul><li>C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O  G = -2870 kJ/mol </li></ul><ul><li>6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2  G = +2870 kJ/mol </li></ul>Δ G = G final – G initial
    17. 17.  G 20 240 140 20 140 240 Δ G = G final – G initial Please determine the activation energy and Δ G
    18. 18. Equilibrium Equilibrium reactions convert back and forth with minimal energy. For equilibrium reactions:  G = 0
    19. 21. Adenosine Triphosphate <ul><li>ATP is the primary free energy source for cells </li></ul><ul><li>ATP ADP + P i </li></ul><ul><li>+ energy </li></ul><ul><li> H 2 O </li></ul><ul><li> G = -31 kJ/mol </li></ul><ul><li>in the cell,  G is closer to -54 kJ/mol </li></ul>ATPase
    20. 22. Phosphorylation <ul><li>ATP hydrolysis does not occur on its own. </li></ul><ul><li>Often, the energy is focused through phosphorylation of enzymes. </li></ul><ul><li>ATP is replenished through cellular respiration. </li></ul>
    21. 24. Redox Reactions <ul><li>reactions involving electron transfer </li></ul>
    22. 25. Redox Reactions <ul><li>Reduction – chemical reaction where an atom gains electrons </li></ul><ul><li>Oxidation – chemical reaction where an atom loses electrons </li></ul><ul><li>L oss G ain </li></ul><ul><li>E lectron E lectron </li></ul><ul><li>O xidation R eduction </li></ul>LEO the lion says GER
    23. 26. Redox Reactions <ul><li>Reducing Agent – substance that LOSES electrons; it causes the other substance to be reduced </li></ul><ul><li>Oxidizing Agent – substances that GAIN electrons; it causes the other substance to be oxidized </li></ul>
    24. 27. Redox in the Cell <ul><li>Many metabolic processes consist of chains of redox reactions. </li></ul>A - A B - B C - C D D -

    ×