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Structure of Atoms .txt | So what holds the nucleus or the protons and neutrons together? |
Structure of Atoms .txt | Well, the force that holds the nucleus together is called a nuclear force. |
Structure of Atoms .txt | This is just one type of electrostatic force and it's a very strong force. |
Structure of Atoms .txt | Now, once again, it's very important to understand the fact that due to the small size of our electrons orbiting our nucleus, the atom is composed mainly of empty space. |
Dalton鈥檚 Law on Partial Pressure .txt | Well, let's recall what the kinetic molecular theory tells us about the behavior of ideal gases. |
Dalton鈥檚 Law on Partial Pressure .txt | Well, it tells us two important things. |
Dalton鈥檚 Law on Partial Pressure .txt | First, gas molecules have no volume. |
Dalton鈥檚 Law on Partial Pressure .txt | And second, gas molecules exert no force on one another. |
Dalton鈥檚 Law on Partial Pressure .txt | That means if we had a system continuing containing two gas molecules, gas molecule A and gas molecule B, that means these two guys have no volume and they exert no force on one another, so they can't communicate. |
Dalton鈥檚 Law on Partial Pressure .txt | So in many different ways, molecule A is invisible to molecule B and molecule B is invisible to molecule A. |
Dalton鈥檚 Law on Partial Pressure .txt | And that leads directly into the following results pressure created by one gas molecule is independent of the pressure created by another gas molecule. |
Dalton鈥檚 Law on Partial Pressure .txt | In other words, the pressure that this gas molecule exerts on the walls of my system of my container is independent of what this guy exerts on my wall of the container. |
Dalton鈥檚 Law on Partial Pressure .txt | So to find the total pressure, my system of two gas molecules, I simply have to add up this pressure and this pressure. |
Dalton鈥檚 Law on Partial Pressure .txt | And that's exactly what B states. |
Dalton鈥檚 Law on Partial Pressure .txt | The total pressure of any system of gas molecules is equal to the pressure exerted by each an individual gas molecule. |
Dalton鈥檚 Law on Partial Pressure .txt | So p one plus p two plus all the way up to PM, assuming that my system is composed of M gas molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | So this is simply a mathematical way of representing any series. |
Dalton鈥檚 Law on Partial Pressure .txt | So let's look at this system. |
Dalton鈥檚 Law on Partial Pressure .txt | So suppose we have a closed system of five gas molecules, two blue and three red. |
Dalton鈥檚 Law on Partial Pressure .txt | Now, we have two types of molecules and a total of five molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | So my one type is blue. |
Dalton鈥檚 Law on Partial Pressure .txt | My second type is red. |
Dalton鈥檚 Law on Partial Pressure .txt | To find the total pressure of my system here, I would simply add up all the individual pressures. |
Dalton鈥檚 Law on Partial Pressure .txt | So five molecules altogether. |
Dalton鈥檚 Law on Partial Pressure .txt | So I add up to five molecules p blue one plus p blue two plus p red one plus p red two plus p red three. |
Dalton鈥檚 Law on Partial Pressure .txt | Now, I could also say that my p total is equal to the pressure due to blue gas molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | This guy plus this guy plus the pressure due to red gas molecule or p one plus p two plus p three. |
Dalton鈥檚 Law on Partial Pressure .txt | Another way of saying this is the pressure due to my blue gas molecule is the partial pressure of my blue molecule and this guy is the partial pressure of my red molecule. |
Dalton鈥檚 Law on Partial Pressure .txt | So partial pressure refers to the pressure exerted by one type of gas molecule. |
Dalton鈥檚 Law on Partial Pressure .txt | In this case, a blue gas molecule or a red gas molecule in a mixture of gases. |
Dalton鈥檚 Law on Partial Pressure .txt | In this case, two types of gas molecules, red and blue. |
Dalton鈥檚 Law on Partial Pressure .txt | So another way of representing this formula or equation is the following. |
Dalton鈥檚 Law on Partial Pressure .txt | So we can represent the partial pressure of any gas in a mixture of gasses by the following equation. |
Dalton鈥檚 Law on Partial Pressure .txt | The partial pressure is equal to the mole fraction of that gas in our mixture times the total pressure. |
Dalton鈥檚 Law on Partial Pressure .txt | In other words, I want to represent this in this following way let's see what we do. |
Dalton鈥檚 Law on Partial Pressure .txt | P total is equal to well, how many blue molecules on the system? |
Dalton鈥檚 Law on Partial Pressure .txt | Two. |
Dalton鈥檚 Law on Partial Pressure .txt | How many molecules altogether? |
Dalton鈥檚 Law on Partial Pressure .txt | Five. |
Dalton鈥檚 Law on Partial Pressure .txt | So the mole fraction of my blue guy is two over five times my P total plus the partial pressure of my red molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | We have three red molecules over five red molecules times the P total. |
Dalton鈥檚 Law on Partial Pressure .txt | So this is the partial pressure due to the blue molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | These guys are the same plus the partial pressures into the red molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | These guys are also the same. |
Dalton鈥檚 Law on Partial Pressure .txt | Gives us P total. |
Dalton鈥檚 Law on Partial Pressure .txt | And look, common denominator adds a two and three. |
Dalton鈥檚 Law on Partial Pressure .txt | I get five and five. |
Dalton鈥檚 Law on Partial Pressure .txt | The five cancel and I simply get P total equals P total. |
Dalton鈥檚 Law on Partial Pressure .txt | So this formula makes sense. |
Dalton鈥檚 Law on Partial Pressure .txt | And in fact, this formula is called a Dalton's Law of partial pressures. |
Dalton鈥檚 Law on Partial Pressure .txt | And this law can be derived using the ideal gas law. |
Dalton鈥檚 Law on Partial Pressure .txt | And let's see how. |
Dalton鈥檚 Law on Partial Pressure .txt | Well, suppose in part E, we have three types of gas molecules and each type has N number of moles. |
Dalton鈥檚 Law on Partial Pressure .txt | So n one, N two and n three. |
Dalton鈥檚 Law on Partial Pressure .txt | So red molecules, blue molecules and purple molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | Well, what's the total number of molecules or moles in molecules of my system? |
Dalton鈥檚 Law on Partial Pressure .txt | Well, in this case, it was two plus three. |
Dalton鈥檚 Law on Partial Pressure .txt | So we added them. |
Dalton鈥檚 Law on Partial Pressure .txt | So we do the same thing. |
Dalton鈥檚 Law on Partial Pressure .txt | We add the moles, add the number of molecules. |
Dalton鈥檚 Law on Partial Pressure .txt | The N total is n plus n one plus n two plus n three is my total. |
Dalton鈥檚 Law on Partial Pressure .txt | So, if I want to find the total pressure using the ideal gas law, the following has to be done. |
Dalton鈥檚 Law on Partial Pressure .txt | I rearrange it a bit and bring the D over on this side. |
Dalton鈥檚 Law on Partial Pressure .txt | And again, P total is equal to while my volume is constant, I'm assuming it's constant. |
Dalton鈥檚 Law on Partial Pressure .txt | My temperature is constant. |
Dalton鈥檚 Law on Partial Pressure .txt | Also, R is a gas constant. |
Dalton鈥檚 Law on Partial Pressure .txt | It's always constant. |
Dalton鈥檚 Law on Partial Pressure .txt | And now I plug in N total or the total number of molecules in my system. |
Dalton鈥檚 Law on Partial Pressure .txt | Now I can go to the next step. |
Dalton鈥檚 Law on Partial Pressure .txt | And instead of writing N total, I plug in all these three guides or the addition of these three guides and I get in parentheses n one plus n two plus n three times RT divided by V.
And now I need simple algebra to distribute to each guide. |
Dalton鈥檚 Law on Partial Pressure .txt | And I get n one R T over V plus n two r T over V plus n three r T over V. And we see using the ideal gas law that we get the same exact thing as up here. |
Dalton鈥檚 Law on Partial Pressure .txt | So P total is equal to partial pressure of gas one plus partial pressure of gas two and plus partial pressure of gas three. |
Dalton鈥檚 Law on Partial Pressure .txt | So once again, we found this formula first using the kinetic theory. |
Dalton鈥檚 Law on Partial Pressure .txt | And then we confirm that in fact, this works using the ideal gas law. |
Dalton鈥檚 Law on Partial Pressure .txt | So this formula may makes a lot of sense. |
Oxidation Numbers Example .txt | In this example, we're going to assign oxidation numbers to atoms of molecules. |
Oxidation Numbers Example .txt | Here we have nine molecules. |
Oxidation Numbers Example .txt | So let's begin. |
Oxidation Numbers Example .txt | In this molecule, we have an N atom at an fatom. |
Oxidation Numbers Example .txt | An fatom, according to our table, precedes or is more important than an N atom. |
Oxidation Numbers Example .txt | And that means we first assign our number. |
Oxidation Numbers Example .txt | Oxidation number to F gets negative one. |
Oxidation Numbers Example .txt | But since we have three F's, that means this one has a negative three. |
Oxidation Numbers Example .txt | And since our entire molecule is neutral, this one must be plus three. |
Oxidation Numbers Example .txt | Plus three minus three gives you neutral. |
Oxidation Numbers Example .txt | So zero charge makes sense. |
Oxidation Numbers Example .txt | Let's look at Ammonium NH Four. |
Oxidation Numbers Example .txt | NH four has an overall charge of plus one. |
Oxidation Numbers Example .txt | Now let's look at the atoms. |
Oxidation Numbers Example .txt | Our H atom is more important than N atom, so we assign to H first. |
Oxidation Numbers Example .txt | Since H is not attached to a metal atom, we assign H a plus one. |
Oxidation Numbers Example .txt | So four h is get plus four. |
Oxidation Numbers Example .txt | Since we want a plus one overall charge, this guy must be a minus three. |
Oxidation Numbers Example .txt | Minus three plus four gives you a plus one. |
Oxidation Numbers Example .txt | Let's look at no three. |
Oxidation Numbers Example .txt | This guy has negative three as an overall charge. |
Oxidation Numbers Example .txt | So let's look at the individual atoms. |
Oxidation Numbers Example .txt | All is more important than N. That means we first assign our oval, so all gets a negative two. |
Oxidation Numbers Example .txt | Since we have a three zeros, this becomes negative six for three OS. |
Oxidation Numbers Example .txt | And since we want a negative one overall, our N must be plus five. |