Solvation

Explanation

Solvation, also called dissolution, is the process of surrounding solute with solvent. It involves evening out a concentration gradient and evenly distributing the solute within the solvent.

Transcript

Alright. Let's talk about solvation. Solvation is the process the process sorrounding solute particles with the solvent. So when we are dealing with solutions the solvation actually is what's actually happening within the solution. So we know that the universal solvent is water and we're dealing with water as a solvent. We're going to call that hydration. So you might hear that as well.

Alright. So the phrase like dissolves like, what does that mean? It might be something that your Chemistry teacher might have talked about in class. That actually means, we're dealing with polarity. So we're going to talk about water as a univ- because it's a universal solvent.

Water is a polar substance. Meaning that it has a negative end and a positive end. And so, we want to, anything that's polar has a charge, can dissolve within water. So when we're taking something that's ionic, we know ionic compounds are held together through electrostatic forces and they actually do have positive and negative ions within them, that's what makes the ionic compounds. So when you drop it into water, what happens? Well, these the ions are actually going to separate from themselves and they're going to be surrounded by the water particles. So that oxygen is negatively charged, they're going to surround, they kind of like attack this positive cation and that this is actually the solvation process. And the negative ones are going to be surrounded by the hydrogen. So the more that they're actually like pulling off and actually going away, the more the ions you're exposing and eventually all these will be exposed in water making the whole thing dissolved. Okay? The same thing happens within a molecular solution but you have to make sure the molecular solution is a polar substance. If it's non-polar, this actually won't be able to happen. And what happens is this is sugar, this is table sugar and the table sugar has oxygen and hydrogen bound together. And we know that hydrogen bound together we know will create hydrogen bonding. And so when water comes close to it, this actually will, it will surround it here and here. All over the place. You'll see this bond or this attraction for water with sugar. So when the sugar separates from itself, each sugar molecule separates from itself, water will actually surround it making it dissolvable or dissolve in the solution. So this is the process of solvation. Okay. It's only polar molecules can do this, do this, it's non-polar. they don't have water is not attracted to it at all. So it's not going to surround it at all, so it's not going to dissolve. So that's the idea of the like versus like, sorry, like dissolves like means.

So what kind of factors affect solubility rate? Well, meaning how fast can it dissolve? So if we have the more surface area exposure that this compound has to the water or whatever it's being dissolved in, but they will obviously dissolve faster. So if you think about like a sugar cube versus granular sugar, the sugar cube will take a little bit longer to dissolve than the granular sugar which will be much quicker because it's more exposed. Stirring or agitating it obviously that's why you're - when you're thinking about dissolving something you stir it, that makes sense. That's actually making it more exposed as well. And then heating. When you heat something up, that creates more kinetic energy and things are moving around much more. So, you're able to dissolve this solvation processes if you are able to at a quicker rate.

I come across words like saturated, sorry. Unsaturated, saturated and supersaturated, when something, only a certain amount of substance is able to dissolve in, let's say 100 grams of water. So if it's not to that point, there's actually a point. It's called saturation point and if you get if you don't get there, if you can still do continous to dissolve more sugar or whatever we're talking about in that water, that solution is what we're going to call unsaturated. Meaning you can continously add more solute into the solvent, that solution until you get to the saturation point and once you hit the saturation point, it's going to be saturated. Meaning you can't add any more in there. And supersaturated, what's that? That means like if you heat up the substance the more, the hotter the substance is, the more it's able to dissolve something. So if you heat up the substance and then put in like a certain amount of sugar and then cool the substance back down, that certain amount of sugar is actually too much that cool temperature, but it will stay in solution because you'd have originally put it there. And if you agitate it just a bit, it will start crystallizing out and that's how like things like rock candy is formed or things like that. It's from supersaturated solutions.

And gas solutions are actually a little bit unique too. Let's think about soda as an example. Soda is a typical like gaseous solution within a liquid. And so we talk, let's talk about pressure. So if you have a two litre container of soda, how are you going to make sure that the gas doesn't escape from that soda and make it a non-gaseous solution. Well, you probably want to keep it cold. The colder a solution is, the less movement those gas particles will have to escape. So the colder a solution is the more it will stay in solution and not only that. The more pressure you have in that solution the more those gas particles will want to stay in that liquid. they're not going to escape. So those kind of things are unique within gases.

So the more, actually, the higher the temperature of the gas is, the solution with the gas is, the worse it is for that gaseous solution. It will actually like not be able to dissolve as much. So it's kind of the opposite as you would think to other types of solutions. So it is unique in that way.

So these are the properties and the reasons things dissolve in other solutions and it's called solvation.

Types of Solutions

Explanation

Solutions are homogeneous mixtures. Different types of solutions have solvents and solutes in different phases. Solutes are dissolved in the solvent. In a solution in which carbon dioxide is dissolved in water, the water is the solvent and the carbon dioxide is the solute. Two important concepts in studying chemical solutions are solution concentration and solubility equilibrium. Properties of solutions as a whole are called colligative properties.

Transcript

Alright. Let's talk about the different types of solutions that you'll see. Don't forget a solution is actually a homogenous mixture meaning that there are actually things within a solution not bonded together. They're just kind of, they're attracted to each other in a way that this makes it the same throughout.

Different types of words that you'll see when you're dealing with solutions are words like solute and solvent. A solute is actually dissolved within the solvent. So whatever is being dissolved is a solute, what it's being dissolved in is a solvent. The universal solvent that is that you'll come across is water and that makes sense since most things are dissolved in water, but there are other types of solutions that you'll see too. One being gas dissolved in gas and that think, you know think about the air we breathe is a mixture of gases. Gas dissolves in liquid and soda is a great example of that, the ga- carbon dioxide bubbles. They're actually gaseous or dissolved in liquid of the soda.

Then we have the liquid dissolved in liquid. Juice is a good example of that. some fresh squeezed juice or something along those lines. You can have solid dissolved in liquid which is like our sugar. Our sugar is going to be our solid form, dissolved in our liquid tea, that would be our. They do actually see this actually quite often solid dissolving in liquid.

Solid dissolving in solid. Steel or any type of metal alloy actually is a mixture of solids.

Gas dissolved in solids like foams or marshmellows. So these are different types of mixtures that you'll see in different mediums that they're actually in, and there are different words that we actually may come across too. Soluble versus insoluble and when you're dealing with double replacement reactions you'll have a precipitate. Precipitates are insoluble meaning they come out of solution. If something is soluble, it means that it's actually dissolved within the solution it doesn't come out, it's still within the solution.

You may see the word miscible versus immiscible. This miscible you can kind of sounds like mixable. That's exactly what it means. If something's miscible, they actually it's something they can mix together. If they're immiscible like oil and water, they are actually not able to mix together. So these two, these four words you might see quite often when you're dealing with types of solutions.

Chemical Solutions-Osmosis

Chemical Solutions

Osmosis

Explanation

Osmosis is the diffusion of water molecules across a semi-permeable membrane from an area of high concentration to an area of low concentration. In cells, osmosis occurs across the cellular membrane to keep a cell from becoming flaccid (not enough water) or turgid (too much water).

Transcript

So osmosis is the diffusion of water through semi permeable membrane. And this is something that a lot of teachers will spend a little bit of time on but then they'll hammer you with on a test. Because it is really kind of unusual when you first approach it a lot of kids don't really get what it means, but to the teachers it's pretty obvious. So let me see if we can help you figure this out. So what this is all about is a special case of diffusion, you know diffusion is but why is it specifically water? And that's because water has the ability to go through a number of different membranes. This black line here that I drew in I'm using it to represent some kind of membrane. Well it's a cell membrane, a special kind of plastic or dialysis tube whatever.

You'll notice that there're small holes in it, I've used red to represent sodium ions they're too large to fit through these holes I've used blue to represent water. It's easily small enough to fit through so what happens is that like all other molecules water does diffusion and you know diffusion is the movement from an area of high concentration to an area of low concentration. So what we see here is that the water starts to diffuse from there's 90% water to where there's 70% water why because that's what molecules do. So the water tends to go like this now does all of the water go no. if I look at just this one area here if this is 90% then let's suppose I'll make up a number of 90 molecules of water going that way at the exact same time 70 of the water molecules over here are going back. 90 go this way 70 go that way there's a net difference of regaining 20 on this side. Now the sodium it trys to diffuse but like my friend 2 ton Tony he can't fit through the opening of the door way so he gets he bounces off and stays over here. This sodium tries to move but it bounces off because it can't fit through.

And that means that ultimately we see the water moving from this side to that side while the sodium stays and as this will continue going until the water wound up diluting out the sodium on this side equilibrating its concentrations. That's osmosis now as I said teachers love to ask a bunch of questions about this so I'm going to give you the 3 basic questions that they'll generally ask about osmosis. Now to do this I'm going to be introducing some vocabulary, this stuff about tonic. Now tonic is a root word that means pull I think in Latin I'm not sure it's all Greek to me. But what I'm going to do is I've drawn here 3 different circumstances this little black circle here that's in my beaker of water let's say that's a red blood cell alright, all of these red blood cells have 80% water 20% other stuff. I don't care what it is it's just not water, so they're all the same however I plunked them into 3 different kinds of solutions.

This is pure water as you can see its 100% water, 0 stuff, this is 80% water 20% stuff, this is 60% water 0% stuff. Let's take a look at this one right here every second some of the water molecules move out but some of the water molecules move in, what's the net change? Well 80 move in as 80 move out so there's no change, the salt and other proteins and other things that cannot pass the membrane they stay so we're only looking at the water because this is osmosis. Because we see no change because both sides have the same amount of pull tonic ability we call them isotonic. Isotonic means that it has the same concentration of water and solutes let me use the red pen to represent solutes alright. What about this situation, well 80% inside 100% outside 80 move out 100 move in.

What's going to be the overall change, water is going to continue moving in and in and in this is going to make the cells to go, swell up and a red blood cell doesn't have the ability to do anything else like start shoving some of the salt out so it's going to pop. Because this outside water solution doesn't have any ability to pull water into it in fact it's pushing water out it's called hypotonic. Because it has lower than the normal amount of pull compared to the cell. It's always in comparison, it's kind of like saying taller, somebody can be taller or shorter than someone else. You can ever just say that person is taller, so hypotonic says, means it has less concentration of solute more water. Okay if we take a look at this one this has 80% water on the inside, 60% water on the outside because there's a ton of other stuff say salt or whatever. So we have our water move out 80 move out 60 move in we have a net movement out of the cell. So in this case instead of popping sometimes it's called liaising.

Here it starts to shrivel, if it's a plant cell they don't say that plant shrivelled they say that plant wilted. And if it's a red blood cell and the other word that you'll see beside shrivel is crenate I don't know why people keep coming up with these words just to confuse you guys. So this one, this solution outside the cell has a greater pull and excessive pull and it pulls all the water out tonic means pull. What is excessive what's the root with that means excessive? Well you have known that hypo meant below as in hypothermia. What means excessive hyper like your brother, he is hyper active so this has a hyper excessive pull. So hypertonic solution has more solute less water, so that's how you do osmosis alright so in an isotonic solution a cell will just stay the same it'll be an equilibrium. A cell in a hypotonic solution will swell up and if it's a plant cell its wall will keep it from bursting but animal cells will typically pop especially red blood cells. And a hypertonic solution a cell will shrivel or wilt.

Phase Diagrams

Explanation

Phase diagrams graphically depict the state of matter in varying temperatures and pressures. The x-axis of a phase diagram is always temperature while the y-axis is always pressure. There is a point on a phase diagram called the triple point at which all three phases of matter exist simultaneously.

Transcript

So we're going to talk about phase diagrams, phase diagrams are graphical interpretation of pressure versus temperature.

okay so basically you can fig- you can figure out if you don't know the temperature or pressure of any substance you can figure out which phase it is using a phase diagram so and we also can see what pressure and temperature is needed for different phase changes going from solid to liquid to vapour so let's like let's look at this graph in itself and try understand what this is saying, so we have 3 major lines here we have one going up this way and we have one coming down here so this, this separation here between the solid and vapour, this point where if any time they crosses this line, we're going to have sublimation occuring. Any time it crosses this line here it's going from a solid to a liquid or liquid to solid either way, we're going to have either freezing or melting going on. Notice that one atmosphere which is that we know one atmosphere in 0 degree Celsius is our normal freezing point and melting point.

Any time that you have temperature pressure within this region your substance will be so- will be a liquid anything down here is starting to be a vapour or gas. We have the reason why we call this normal is because one atmosphere we call this normal atmosphere pressure and we also know this is our boiling point at 100 degrees Celsius we know the water at a 100 degrees.

Okay there are a couple other things in here that you might not know, one is when they're all in a centric here that was what we called the triple point actually there is a there is a temperature and pressure at which all three phases will coexist together and we're going to call that the triple point.

There's also something up here called the critical point, the critical point is a place where anything any pressure or temperature that's higher than the critical point there's no way liqu- the liquid phase will exist it will only the substance will only exist in the gaseous phase so this actually kind of tells us a lot of things in terms of subst- which where the substance is in terms of the state of matter that is in.

Alright, so let's look at something else, this was water, so let's look at something else, it's another phase diagram we can talk about each substance has its own phase diagram and this is carbon dioxide and there is a couple differences in carbon dioxide than there was in water one main difference if you look at both of them, one main difference is this line here okay notice this line versus this line okay water is very unique in the sense that it will have its solid form is more dense sorry lesser dense than it's liquid form so as we continue to add pressure to the solid formula it will actually change to a liquid state and if we continue to add pressure you notice it'll go up its going to eventually change into liquid state because liquid state actually more dense than the solid state whereas in most substances if you increase pressure it's going to stay in it's solid state because the solid state is actually more dense than liquid state so you're going to see a line looks like this.

Alright notice carbon dioxide we're going to call that dry ice carbon di- the reason we call it dry ice is because here we have some dry ice actually with us, let me get some out for you alright the reason why we call it dry ice is because we have it a solid form but yeah it's sublimate meaning it goes straight from solid to gas okay this is used sometimes in like movie studios or to make that gas the gas appearance the gaseous appearance, so if you notice this goes straight from the solid state skip skipping the liquid state going straight to the solid state I mean straight to the gaseous state and we call this sublimation. Alright so we're going to actually demonstrate with triple point will look like by putting dry ice in this container and seeing if we can make it liquid somehow so let me try and put my safety goggles on because safety is always first and we are going to put some little pieces of, we're going to, this is really cold so I really shouldn't be doing that but it's not going to hurt me unless hold it for too long, little pieces [IB] alright so what I'm going to do with this oops I'm going to, alright so what I'm going to do with this is I'm going to close this up and so now I have my dry ice in here and my dry ice is sublimating as you saw before and so it's going straight to a gaseous state meaning and also making a pressure inside this container much higher okay so if we look back and if you remember back at our graph you notice this is continue still sublimating, okay and what we want to do is we want to continue the to make the pressure high enough where it will sublimating and actually go to a triple point where we can see all these in the same time and how we're going to do that is going to lower the temperature and notice from the side we notice that inside this container is really cold as you can see from the impressions of the bottle and also as you can imagine its getting really pressurized in here because the gas is continuing to sublimate and this is going to increase the pressure inside the bottle so hopefully we'll get to the triple point, we can shake it up a little bit as you can see like on the side over here maybe you can see like the liquid inside here so now all three phases are existing making this the triple point. We can see in the bottom like maybe some liquid here, liquid CO2.

Alright so now we're going to open the bottle and see what happens whoo and this is all the gas that's escaping there's a tons of pressure in here they're 5 atmospheric pressure which is 5 times the regular atmosphere that we actually living in at sea level so actually let's go back here and just make sure we understand what will happen is here is our normal temperature around here we know that [IB] sorry carbon dioxide is in gaseous state what we did we lowered the, the temperature by putting it inside the container and make increase of pressure as it sublimates inside the pressure and we're able to create the triple point where all threes substances coexist, so this graph actually tells us a lot of things about the different types of substances in different types of forms that they can actually have in pressure and temperature and how they're related.

Phase Change

Explanation

Phase changes are the transformations from one state of matter to another due to thermodynamics. The processes of phase change between solid and liquid are called melting and freezing. Phase changes between liquid and gas are vaporization and condensation. Phase changes between gas and solid are deposition and sublimation. Phase changes can be spontaneous or non-spontaneous.

Transcript

We're going to talk about phase changes, going from different forms of matter; for the solid, liquid gases and how they interact with each other and how they change from one phase to another. So let's use this as an examp- as a good diagram to show us how these things interact with each other.

Alright, so if we're going to get from solid to a liquid we're actually call that melting which I know we've heard that word many times before and that actually requires energy, we need heat to melt something, so we're going to call that endothermic process meaning that it requires energy or requires heat for that reaction or that that phase that to occur. So if we're going to from liquid the opposite from liquid to solid, we're going to call that freezing which I know we've heard many times before too. That actually releases some sort of energy, it's going to be an exothermic process, meaning it releases energy. These guys are opposite of each other, melting and freezing, of the same thing.

Let's go over to liquid and gases. If we're going from liquid to gas, we're going to call that vaporization; we're going to vaporize that particular liquid. That actually, requires energy as well. We need heat or some sort of energy to make that happen. So we we're going to call that endothermic process. The opposite will be cond- condensation; when we're are condensing something from a gas down to liquid and that's an exothermic process meaning that's going also to release some sort of energy.

There are rare instances where substances will go straight from the gas phase to the solid phase. It doesn't happen as often as you probably know but they do happen with different substances so if we're going from the gas phase down to the solid phase, we're actually going to release that sort of energy because we know gas is in high has higher energy than solid phase so we're going to release that energy we're going to call that process deposition. The opposite would be sublimation going from solids to a gas we've seen this probably before when ice or solid CO2 maybe iodine crystals they go from this solid phase straight to the gas phase skipping over the liquid phase that actually it releases sort releases some sort of energy and that we call it endothermic process.

Alright so let's actually look at this in a different way this you might see more often in class. This is actually a different a graph describing all those things that we just talked about. Alright so on the x ax- sorry on the y axis we have temperature on the x axis we got x axis we're going to have energy okay so we know in this case we're going to talk about water the phase change of water and we know that below 0 degree Celsius that is in solid phase okay? So as we increase energy, our temperature of that solid is going to increase until we hit 0 degree Celsius which we know it is melting and freezing point s the increase if we increase energy it's going to melt and if we're going from liquid to solid it's going to start freezing but notice the temperature it's not changing even though we're increasing temperature why is that? Well that energy that we're pumping into the into this solid molecule this substance is actually being used to break up those intermolecular forces that are holding it together in a solid so here's the picture water and these blue dots are the hydrogen bonds that are holding it together in a solid so because solids have more hydrogen bonds than liquids that energy is going to be used to break up some of those bonding some of those forces that are holding it together. Then as you go from 0 degree Celsius to 100 degree Celsius we're going to be in a liquid phase all that and all the energy is going to be used to increase the temperature of that particular liquid in this case water. And here we have the same thing we have this plateau and 100 degree Celsius we know that is it's vaporization point or it's con- condensation point again it's flat and again that energy is being used to break apart more of these hydrogen bonds once at 100 degree Celsius these bonds are going to be pretty wear because their energy is being used to break them apart and have them flow around allover the place and then up at higher temperatures above it's always going be in a gaseous phase.

If we go straight from the solid to a gas which water doesn't do if it were to we would call that sublimation going to skipping this liquid phase completely, if we're going from gas to solid we're going to call it deposition we're going to complete again skipping that liquid phase so this actually cycle talks about the different phase changes that substances tends to undergo.

Kinetic-Molecular Theory-Three States of Matter

Three States of Matter

Explanation

The three states of matter, also called the phases of matter, are solid, liquid and gas. Matter changes phases based upon thermodynamic principles like enthalpy and entropy. At room temperature, different elements are in different states because of their intermolecular forces.

Transcript

Alright so we're going to talk about the three states of matter; solids, liquids and gases and we're going to start off with solids.

Solids have a definite shape and a definite volume as you should know but are these particles in motion? Your first thought might be no they're not in motion but in actuality they are. All the bonds and all the atoms actually have constant vibrations going on within the atom within the solid. We might not be able to see them or detect them but they actually are happening at the atomic level. The only time these vibrations actually cease is at zero Kelvin or absolute zero or -273 degrees Celsius and in reality we actually would never even reach that point so in reality that is actually like a theory it's a theoretical point so yes all of these particles are still in motion and what's up with the density? The density of solids you're, we think the density is actually the compaction or how tightly closed these particles are to each other in a given volume so solids you would think have actually mostly most of them do have a higher density than their liquid and solid counterparts except in water. Water is a rare exception where the density of the solid or ice is actually lower than the density of the liquid that's not the way that hydrogen bonds and the way it actually like forms its solid its actually less dense and its liquid which is the reason why ice floats. Most solids actually don't float in their liquid.

Let's talk about the different five, the five different types of solids you might come across in Chemistry class the first one being atomic solids. Atomic solids are just atoms that are that are attached to each other in a solid form they are they're pretty soft they have a low melting point and they're actually a poor conductors meaning they do not conduct electricity they don't they don't have those free floating electrons that are able to conduct electricity. These are atoms might be group 8 elements neon, argon things like that. They actually form atomic solids.

Next would be molecular. These molecular compounds come together and they're intermolecular forces are what's keeping them all together, their molecules also take place in this and those are guys they're fairly soft they too have a low melting point and they also do have poor conductivity because they don't have these free floating electrons and those are typical things like water, sugar, ammonia things like that, there's there's molecules that are held together through IMFs or through intermolecular forces hydrogen bonding.

Next would be covalent network solids and those are just strictly atoms all covalently bonded to each other so not just atoms held together through the lack of energy it's actually they're all bound to each other they're sharing each others electrons. These guys are really hard molecules because they are all covalently bound, they have a high melting point but they're still poor conductors because they are there's no electrons there to like give it give electricity out and things like these are diamonds carbon the carbon in diamonds are all covalently bound to each other to give it's shape and quartz, silicon dioxide actually is cova- covalently networked a covalent network solid. Things in group 4 typically, group 4 has like carbon and silicon all have covalent network solids.

The fourth one is ionic compounds; ionic compounds are ion, ionic solids are all made up of their ions cations and anions all bound together through electrostatic forces. These guys are hard, they're brittle, they have a very high melting point it's really hard to separate those ions from each other and they too are poor conductors when they're in a solid state. If you put their solid state in water making it a solution, that actually makes their conductivity extremely high because those guys separate from each other and we have those access to those electrons but in just the solid itself, they're actually very very poor conductors. Any type of ionic compound is what I'm talking about; table salt, calcium carbonate things like that anything that's ionically bound to each other.

Lastly we have metallic bonds, metallic bonds are made up of all metals and the reason I have sea electrons here is because its how metallic bonds actually are created are through the they're held together to their positive ca- cations and their valence shell electrons are kind of make the sea of electrons to delocalize electrons share it all throughout the whole solid so that's why the sea of electrons comes from and because they have this like flow of electrons within the solid, they have extremely good conductivity they're good conductors of electricity which is the reason why become coming from those free flowing electrons within the metal. I mean any and all metals actually make metallic bonds are metallic solids.

Next type of phase is liquids, liquids have no definite shape and they do have a definite volume. They have characteristics one of them being fluidity. Fluidity means the ability to flow so things that they have over solids is they actually can flow over it over themselves along along with gases, gases can do this too, gases can actually deal with this better than solids can oh sorry than liquids can. But the opposite of fluidity is viscosity its how much resistant to flow it is how slimey it is how much it doesn't like to flow so the bigger the size the larger the viscosity or the larger the more likely it won't flow so let's take these these a hydrocarbons for example. This large hydrocarbon is not going to flow as much the intermolecular forces the London dispersion forces that hold these guys together are actually a little bit stronger here because there's more electrons than in its smaller hydrocarbon over here. This guy actually has a lower lower viscosity meaning its flow is greater than this guy which has a higher viscosity. As you increase temperature, the viscosity also decreases so if you increase temperature its fluidity does increase its able to flow more its able to break those IMFs or those intermolecular forces unable to flow more making visc- viscosity lower. Yeah so these are indirectly related and these guys size and viscosity are directly related.

One of the last thing we're going to talk about in liquids is surface tension. And surface tension is inward the measurement of the inward pull of a liquid upon itself so I have one small illustration down here for you to illustrate this. These guys are all water molecules and we have a negatively charged oxygen a positive charge hydrogen and these dotted lines are hydrogen bonds that detect that that that it does attach them but like bring them together and so then what happens here are the surface of the water so here is the water down here and here is like air. If you're going like a crick walk and if you're go you're going like hike in the woods you might see you might come across a pond and you like see bugs kind of walking on water, how do they go about doing that? Well here is an example of a bug's leg and notice the bug barely touches the water and it has a very very small place where it touches the water on it's leg and because it has a small place this hydrogen bond actually keeps the water together and its able to make the bug walk on top of it that's because the surface tension or this or this bond is actually not bond but its attraction. It's actually pretty strong compared to this light weight of this bug so it holds it up so this surface tension is different for each kind of liquid water has a pretty good surface tension so its able to hold the bug's like on top of it.

And lastly are gases, gases have no shape and no volume and there's actually a whole ton of laws and a whole ton rules that's dealing with gases and their behavior and we're going to go into that in the next couple of videos so this actually in a nutshell talks about the three states of the matter; solids, liquids and gases and hopefully this makes sense.

Decomposition Reaction

Explanation

A decomposition reaction is a reaction in which a single reactant produces multiple products. An example of a decomposition reaction is when water is broken down into hydrogen and oxygen. In essence, decomposition is the opposite of a synthesis reaction.

Transcript

Alright, so one of the types of reactions that you'll see in class are decomposition reactions and decomposition reactions are exactly the way they sound. It's going from a single reactant going to several products. Like when you think of something decomposing like trash or your biodegradables or whatever it maybe you think of something you trash breaking down into it's elements and several different products, which is exactly what's happening. You have one reactant, that's your key this is going to be your clue that it's a decomposition reaction breaking down into several products. So here's your skeletal reaction notice it's one reactant key key key to your several products.

Okay so what we're doing is we're going to be breaking the bonds and breaking bonds requires a lot of energy. So what sometimes you'll need to make this go faster is you'll need something called a catalyst. And a catalyst is something that speeds up a reaction and actually lowers the activation energy so you don't have, doesn't require as much energy for this reaction to occur and it actually speeds up the reaction process. So catalyst are typically used in decomposition reactions. So here are some examples of what you might see in class, you have your single reactants breaking down, you can break down to elemental form from sodium nitrite to sodium and nitrogen. It can break down to 2 compounds dinitrogen oxide and water or it can even break down into elements or elements and water, it really depends on what your reactant is.

Alright so let's actually talk about this in a little more depth, this is hydrogen peroxide you probably have it in your medicine cabinet at home and what happens if you keep it too long this reaction will actually take place and it'll break down into water and oxygen gas. So you don't want to keep hydrogen peroxide too long or else it's going to lose its effectiveness essentially and you're not going to be able to use it anymore. So you're going to make sure that you actually replace this quite often because this reaction does take place now it does take a while to do this but it will do this. So sometimes to make the reaction speed up we talked about using a catalyst. Let's actually do this breaking down into water and oxygen gas.

Let's actually do that with a catalyst and see what happens. Okay so right here we're going to call this Elephant tooth paste and you'll see why, so we're going to have a very strong highly concentrated hydrogen peroxide into our graduated cylinder we're going to add some dish soap just for fun and some food coloring just to make it more fun. Okay and then we're going to add our catalyst, potassium iodide is going to speed up the reaction and notice it goes right away and the soap is actually getting the bubbles from oxygen gas and then you'll also get water at the bottom and so this is an example of a decomposition reaction just in for a fact that the soap is in there to make it more fun. And here's another, there's another good one. Alright so this is, yeah so decomposition reactions are one of the 5 that you'll see in class.