56 Comments

  1. Hi there.
    Really great video which forces me to figure out something that I could not understand previously; that "Gibbs Energy" (and I suspect Helmholz energy too) is a proper title for chem reactions, whereas "work" = dW = pdV is a more suitable term for an engineering process!!! Please, confirm if I am right.
    Now, allow me to make a comment and set a question. At 11:45 you state ΔG < 0 is the energy from the sun and you imply that this is Gibbs free energy. But I think that (according to the previous diagram and your spoken words) this energy is called the "Activation Energy" which we get it from the sun. You state: "…. Now where do we get the activation energy? In photosynthesis, we get it from the sun!". I think that activation energy has nothing to do with Gibbs free energy. This has to be just the so described "Activation Energy". Unless, of course, we perform integration under the whole curve as follows: ΔG = integral(Free Energy* dReactionProcess, limits: G_start, G_end), where dReactionProcess -> infinitesimal ReactionProcess. In this case, yes, we take into account Activation energy, and goes embedded to the final ΔG.
    In both reactions (respiration and photosynthesis) it is not quite clear if we take into account Activation Energy while calculating ΔG. But I think that what matters is just the initial and final values of Gibbs free energy. ΔG just equals to G_end – G_start, that is, ΔG = G_end – G_start, where no activation energy is been taken into account in both processes. This is what I vaticinate.

    Is this correct?

    Thank you very much.

  2. YOOOO TO ALL YOU FUCKERS TAKING THE AP CHEM EXAM IN 2018 THEY CHANGED THE PHRASING OF "SPONTANEOUS REACTIONS" TO "THERMODYNAMICALLY FAVORABLE" ITS FUCKIN WHACK

    okay i've done my duty

  3. Maybe it's irrelevant to say, but when the bomb blew up making some noise, I got back to the Earth again, it really caught my attention.

  4. Finally activation energy. So why is this energy so evasive in chemistry? I was searching for the energy required to initiate a reaction of diatomic hydrogen with diatomic oxygen at 25 Celsius, 1bar pressure in a ideal 2H2 to O2 ratio resulting in H2O.

  5. I guess a lot of people are confused about the slide example and so I'll try to clarify:

    He said the total energy of the system (the ball) decreased, not the total energy of _everything_.

    as in: the energy has been lost from the system, i.e. the ball, as it has come to a stop and reached a stable, stationary, low energy state after all that movement. The energy it lost to reach a position of rest (through friction etc) is the same energy the surroundings gained.

    Hence:
    – the system's (the ball) energy reduced
    – the surrounding's energy increased by the same magnitude
    Conclusion: total energy of the system+surroundings remained the same but the total energy of system (ball) reduced.

  6. If you take the ball and slide to be your system, then it has negligible gravitational potential energy since gravitational potential energy only applies to objects within a system, thus the only gravitational potential energy would be between the ball and the slide. So if you leave the earth out of the system, it would just do work on the ball as it rolls down the slide and increases in kinetic energy, but you can't use the gravitational potential energy between the ball and the earth.

  7. At 9:56, why does the free energy curve increase further than the end before its resulting free energy level (photosynthesis)?

  8. Honestly, this is the first time I've understood what's going on when someone says "Gibbs free energy." An absolute legend

  9. Wow, man ,thank you ,may good things happen to you.this video deserves hundreds of ads and plugins.i thank you bro , words are not enough.

  10. Entropy is NOT DISORDER, and Especially NOT RANDOMNESS. Entropy is an index of the DISPERSAL of energy in a system. It has to do with quantized energy levels. If you're claiming to avoid misleading terms, then stop misleading learners by using a definition of entropy which was proposed by Boltzmann in the 1800s, before the Bohr model of the atom was even accepted by the scientific community.

  11. In the example where the ball rolls down the slide, doesn't the total energy remain constant? The loss in potential energy of the ball is equivalent to the kinetic energy of it at the bottom of the slide, along with the energy lost from the ball due to resistive forces (which are still part of the system). Furthermore, even if the ball is brought to a halt, thus losing its kinetic energy, energy must be put into the system to make it stop, keeping the total energy constant.

  12. So actually CO2 is not a bad thing. to have in the atmosphere all we have to do is to increase the green plants. So Instead of trying to push people towards buying electric cars with false presentation of electric cars being eco friendly due to not producing CO2 exhaust gases, governments should stop polluting the air with those airplanes (chem trails) and also stop deforestation. Because, it looks like burning pure hydro carbons, such as alcohol obtained from corn, that will produce only water and CO2. is the only way to produce recyclable end product via green plants, by using internal combustion engines.

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