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FeJ1LQe6Zh4-000|Let's look at a cell potential of 0.5 volts for the oxidation of bromide by permanganate.
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FeJ1LQe6Zh4-001|The question I have is what pH would cause this voltage?
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FeJ1LQe6Zh4-011|We're looking at the oxidation of bromide by permanganate.
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FeJ1LQe6Zh4-012|And we find that cell is operating at 0.5 volts.
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FeJ1LQe6Zh4-013|So how can that happen?
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FeJ1LQe6Zh4-014|Well, let's look back at the standard reaction.
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FeJ1LQe6Zh4-017|Well, you could raise the reactant concentration.
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FeJ1LQe6Zh4-018|Raising the reactant concentrations would increase the potential for the reaction to go.
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FeJ1LQe6Zh4-019|So let's look at that.
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OkoFU7hocpc-000|If I take hydrogen molecules and oxygen molecules and put them in a balloon, I can pretty much wait forever and they don't form water molecules.
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OkoFU7hocpc-001|That reaction is favorable, but there is a barrier in between that prevents the rapid room temperature conversion.
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OkoFU7hocpc-002|It turns out though that hydrogen and oxygen can be made to form water, release the same amount of energy at room temperature.
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OkoFU7hocpc-003|You can do with a process called catalysis.
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OkoFU7hocpc-004|Catalysis lowers this energy barrier.
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OkoFU7hocpc-005|When you lower that energy barrier, that allows particles-- maybe even at room temperature kinetic energies-- to get over the barrier and form products.
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OkoFU7hocpc-008|So catalysis lowers the energy barrier between products and reactants.
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OkoFU7hocpc-009|It allows a low road path between the products and reactants.
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OkoFU7hocpc-010|And allows reactions to go at much lower temperatures and much more quickly.
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wcMCDbnuNms-000|When an electron is bound around an atom, an electron has wave-like properties.
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wcMCDbnuNms-001|It's bounded, and when you bounce something with a wave-like property, you naturally get quantization, different energy levels.
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wcMCDbnuNms-002|Now, our energy levels are described by wave functions with three quantum numbers-- n, l, and m sub l.
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wcMCDbnuNms-003|And there's a myriad of possibilities.
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wcMCDbnuNms-004|So what we want to do is catalog them and see which energy levels an electron will exist in about an atom.
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wcMCDbnuNms-005|So let's start with the n equal 1 state.
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wcMCDbnuNms-006|n gives the total energy of the system.
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wcMCDbnuNms-007|Now, you can also have m equal 2 and keep on going, up to the ionized state, n equal infinity.
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wcMCDbnuNms-011|The lowest energy orbital about an atom is n equal 1, and the only possible value of l is s.
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wcMCDbnuNms-013|And m sub l is also 0.
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wcMCDbnuNms-014|And the only possibility is 0, so we just leave that off.
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wcMCDbnuNms-015|If you go to n equal 2, you can also have an s.
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wcMCDbnuNms-016|So n equals 1 and n equals 2 both give rise to a spherically symmetric s orbital.
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wcMCDbnuNms-017|But when n equals 2, you can also have l equal 1.
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wcMCDbnuNms-018|l equal 1 has three values of m sub l-- m sub l minus 1, 0, and 1.
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wcMCDbnuNms-019|These are the three equivalent p orbitals.
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wcMCDbnuNms-023|Now, we can continue and go to principal quantum level 3.
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wcMCDbnuNms-024|And a 3 s orbital is also possible.
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wcMCDbnuNms-025|It'll also be spherically symmetric.
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wcMCDbnuNms-027|So the number of nodes increase, but the overall spherical symmetry remains the same.
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wcMCDbnuNms-028|And of course, when n equals 2, you can still have l equal 1.
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wcMCDbnuNms-029|So you'll have a set of 3s orbitals-- 3px, 3py, and 3pz.
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wcMCDbnuNms-030|But when n equals 3, you can also have l equal 2.
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wcMCDbnuNms-032|That gives rise to a set of five different shape and orientation, but equal in energy orbitals.
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wcMCDbnuNms-033|And I have some models of them right here.
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wcMCDbnuNms-034|So one, two, three, four, five d orbitals.
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wcMCDbnuNms-036|And again, when you look in your textbook, these will be given geometric notations-- z squared, x squared minus y squared, et cetera, rather than the m sub l integer values.
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wcMCDbnuNms-037|We do that for purely geometric reasons.
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wcMCDbnuNms-038|The important thing is there's five equivalent orbitals in a set of d orbitals.
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wcMCDbnuNms-039|So you can see an electron can exist in a myriad of different states around the atom.
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wcMCDbnuNms-040|And when you have more than one electron they need to share these states.
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wcMCDbnuNms-041|So that's what we'll look at next.
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ER7lUmsy9m4-000|So let's do that phosphorus oxide reaction in a vessel where we have a fixed amount of oxygen and we add differing initial amounts of phosphorus.
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ER7lUmsy9m4-010|You add a little bit more phosphorus, you'll produce a little bit more phosphorus oxide.
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ER7lUmsy9m4-011|You've used a little bit more of your oxygen.
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ER7lUmsy9m4-013|You cannot produce any more phosphorus oxide.
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ER7lUmsy9m4-014|Oxygen limits the reaction.
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ER7lUmsy9m4-015|It's called the limiting reagent.
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ER7lUmsy9m4-016|So, product will build up until all the oxygen is consumed.
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lItaSuF6Uqg-000|Let's do a calculation where we calculate ionization energy.
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lItaSuF6Uqg-001|We're going to look at a system where we bathe rubidium atoms in ultraviolet light.
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lItaSuF6Uqg-002|That will eject electrons and those electrons will travel off with a certain kinetic energy, and we'll measure that.
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lItaSuF6Uqg-003|So knowing the kinetic energy of the electrons and the amount of energy from the photons of light, we can calculate the kinetic energy.
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lItaSuF6Uqg-005|Let's do a calculation where we calculate ionization energy.
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lItaSuF6Uqg-006|What we're going to do is we're going to take rubidium atoms and bathe them in ultraviolet light.
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lItaSuF6Uqg-007|That ultraviolet light will ionize the rubidium atoms.
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lItaSuF6Uqg-008|Electrons will leave with a certain kinetic energy.
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lItaSuF6Uqg-009|We can measure that kinetic energy.
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lItaSuF6Uqg-010|Now the ultraviolet radiation that comes in has to do two things.
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lItaSuF6Uqg-011|Some of the energy goes into ionizing the rubidium atoms.
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lItaSuF6Uqg-012|The rest of the energy goes into the kinetic energy.
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lItaSuF6Uqg-013|So I know the sum of the kinetic energy and the ionization energy is the photon energy.
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lItaSuF6Uqg-017|So the photon is split into two things, ionizing plus kinetic energy.
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lItaSuF6Uqg-020|Now this is called a photo electron spectroscopy experiment.
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lItaSuF6Uqg-021|Ultraviolet radiation measure the kinetic energy of electrons emitted.
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lItaSuF6Uqg-022|So I know that kinetic energy and the ionization energy add to give the photon energy.
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lItaSuF6Uqg-023|So I can calculate the ionization energy from the photon energy and the kinetic energy.
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lItaSuF6Uqg-024|Kinetic energy of electron at 2,450 kilometers per second, we've done these kind of things before.
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lItaSuF6Uqg-025|1/2 half times the mass of the electron times the velocity squared.
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lItaSuF6Uqg-026|And I write the velocity in meters per second to always operate in kilometers, excuse me, meters, kilograms, and seconds.
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lItaSuF6Uqg-029|So from that and the photon energy, I can calculate the ionization energy.
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lItaSuF6Uqg-030|So the photon energy, I'll cast in terms of the wavelength because that's the parameter I have.
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lItaSuF6Uqg-032|And now I can calculate.
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P_e4n9XSjUw-000|Particles, electrons, small atoms have wave-like properties.
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P_e4n9XSjUw-001|Let's look at that in terms of a chem quiz.
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P_e4n9XSjUw-003|The sodium atom, impacted by the wavelength of light, behaving like a particle, behaving like a photon.
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P_e4n9XSjUw-004|About how many will stop that?
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P_e4n9XSjUw-005|About 1, about 100, about 10,000?
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P_e4n9XSjUw-014|Matter has both wave and particle characteristics.
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P_e4n9XSjUw-015|We've seen the momentum and the wavelength are related by the de Broglie relationship, and we calculated it for several different objects.
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P_e4n9XSjUw-016|Now we're saying, well, a sodium atom is going to be traveling at about 300 meters per second.
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P_e4n9XSjUw-017|It's going to encounter photons of 600 nanometer wavelength.
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P_e4n9XSjUw-018|About how many photons have to strike those sodium atoms to get them to slow down, and about stop?
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P_e4n9XSjUw-021|Those photons of yellow light coming in at 600 nanometers.
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P_e4n9XSjUw-022|We can say, well, I want the momenta of these two systems to be equal.
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P_e4n9XSjUw-023|I want to transfer enough momenta from these waves to stop the particle.
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P_e4n9XSjUw-024|So the wave has a particle nature, it has a tiny little momentum.
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P_e4n9XSjUw-025|I need to transfer it to this larger momentum.
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P_e4n9XSjUw-026|And here comes the sodium atom, I want to bap, bap, bap, bap, bap, bap, bap, bap, bap.
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P_e4n9XSjUw-027|Keep hitting it with photons until-- bap, bap, bap, bap, bap, bap-- that sodium about stops.
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P_e4n9XSjUw-028|And I can do that by just calculating the momenta of each.
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P_e4n9XSjUw-029|And as I do so, I see that the momenta are related by their wavelength by the de Broglie relationship.
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