so in this first example 3.2 we're just going to look at each one of these examples and decide whether or not we have a pure substance excuse me whether or not the pure substance is an element or a compound so our first example is helium gas so helium um this is the the symbol for the element helium and what we see is it is just one type of atom and so because of that it is an element right there is no way for us to break this down uh chemically so this is an element and now sulfur uh would be the same right there is no way for us to break that down into multiple components it's just sulfur so this is also an element now sugar on the other hand is a molecule that is comprised of carbon hydrogen and oxygen so we have three different types of elements in this um in this compound and it is a compound looking at d we have mercury i had to clean up a mercury spill the other day in the lab it's kind of nasty stuff although it's kind of really fascinating at the same time but mercury is just mercury just a single type of atom it cannot be broken down into simpler components so this is just an element and our last example is lye or sodium hydroxide and later on we're going to talk about nomenclature and identifying um covalently bound and ionic compounds getting ahead of myself but um all we need to take a look at is that sodium hydroxide is a molecule that is comprised of sodium and oxygen and hydrogen so theoretically we could break this substance down into simpler components okay the sodium the oxygen and the hydrogen so this is a compound all right so that is just strictly looking at pure substances and being able to distinguish whether or not they are an element okay so we can just look at the periodic table and all of those symbols and identify all of the different elements or if we have a compound that contains two or more different elements example 3.4 classify each of the following as a pure substance or a mixture okay so now we're at the at the first split in our flow chart so um pure substance or a mixture well a soft drink so you know maybe you're you're you're drinking a soda or something right now as you watch this video um and you can go ahead and take a look at the ingredient list right and you see that there are a bunch of different things a lot of sugar that they put into a soft drink we also have the carbon dioxide the bubbles that carbonate the beverage so a soft drink is a mixture of substances okay now propane gas is comprised of both carbon and hydrogen we call compounds that are composed of just carbon and hydrogen hydrocarbons but if you go ahead and get yourself a tank of propane to fuel your grill that tank is going to only contain propane okay not propane and some other stuff just strictly propane so even though this is a compound it is still a pure substance okay we have only one type of compound in in a sample of strictly propane now on the other hand if we have a cheese sandwich well what goes into a cheese sandwich um well we'll take a basic cheese sandwich would at a minimum contain both cheese and bread so this would be a mixture then d we have an iron nail right so here is the symbol for iron um this actually comes from greek ferrous which is why uh its symbol is such um and when we talk about the periodic table um a little bit later on in more detail we'll talk about that um a lot of the elements have symbols um that are just you know the first two letters of their actual name um but some of them do come from i say greek from the latin excuse me from the from the latin terms for these elements um as is the case with iron um but in an iron nail we just have iron okay this does not specify that it's iron with a little something else um that would indicate an alloy so it is just a pure substance now on the other hand a salt substitute so um kcl this is potassium chloride again we will get into nomenclature a little bit later on but um although we do have two different elements in this compound um so it is not an element it is a compound um if all we have is a sample of of potassium chloride with nothing else in it it is a pure substance okay and then um let's see what else we got okay 3.6 a dietitian includes one of the following mixtures in the lunch menu classify each as homogeneous or heterogeneous okay so um as i mentioned um if something is homogeneous that means that although it is a mixture of different substances if we look at it it looks totally uniform okay so just by kind of eyeballing it we can't necessarily tell that it is a mixture of substances whereas on the other hand a heterogeneous mixture we're going to actually be able to identify the different components of that mixture so if we have non-fat milk um right if you pour yourself a glass of milk right that looks completely uniform throughout right milk um if it's fresh doesn't tend to to separate out right and it just looks um totally uniform so this would be a homogeneous mixture on the other hand if we have a chalk if we have chocolate chip ice cream if we look at that ice cream maybe it's chocolate chip and we've got some vanilla ice cream in there but presumably we would be able to identify right oh there's the ice cream and there's the chocolate chips okay so this would be a heterogeneous mixture rouginess okay so we can actually identify the components of the of that mixture at least some of them see a peanut butter sandwich um kind of the same idea if we looked at a peanut butter sandwich we could identify oh there's peanut butter here is the bread so this would also be heterogeneous and then lastly if we had cranberry juice if you poured yourself um some cranberry juice it would look totally uniform uh throughout okay we would not be able to identify the different components of this mixture so although we know it's a mixture right again we can look at the nutrition label and see what all is in our mixture of cranberry juice it would still appear completely uniform so homogeneous okay so this is a a pretty a pretty short video um and i will um make i will make this flow chart available um to you all um i think i'm getting my my my chemistry books mixed up i'm trying to think if there is something similarly useful in your textbook well if there is i will i won't bother um but uh yeah there you go hello everyone this video will cover the information in chapter three section two um so we are going to talk about uh states and property of properties of matter so the three states of matter are solid liquid and gas there is a fourth state of matter uh called plasma um but in general we don't focus too much on that because it's it's well it is becoming more and more part of our everyday lives and different technologies but our focus is going to be on on the three big ones solids liquids and gases and then we'll talk a little bit about chemical and physical properties so i'm looking at example 3.8 indicate whether each of the following describes a gas a liquid or a solid so for a lemonade has a definite volume but takes the shape of its container so whenever we see that we have a definite volume but that a particular substance is taking the shape of the container that it is in that would indicate that we have a liquid now this question kind of gives us a clue because we're talking about lemonade um which i think uh immediately you know we think about having a nice icy glass of lemonade um but it is the fact that uh the substance takes the shape of its container but that the actual volume size does not change so uh liquid for b we have that the particles in a tank of oxygen are very far apart so this is a characteristic of a gas where a sample of gas is not going to have a definite volume but rather it is going to expand in order to fill um you know whatever container that it is held in so this is a gas and in general gaseous particles tend to be quite far away from one another which is not the case in the condensed phases of solid and liquids c helium occupies the entire volume of a balloon so again we have a gas now none of these examples had the answer of solid but for a solid substance we are going to have a definite volume and shape okay so if you just think about you know any uh solid that you um that you have or that you encounter on an everyday life it doesn't matter what you put that solid in um the the shape of it uh does not change um it doesn't expand to fill a container um it just it is what it is so in 3.10 we have described each of the following as a physical or a chemical property and the way that we can distinguish between a physical or a chemical property is that we ask ourselves is this substance fundamentally changed in some way um after undergoing uh this this particular process okay or has it um has it chemically changed is it something different after undergoing this change and so for a we have that neon is a colorless gas at room temperature so what we have here is just an observation um about neon gas that it is colorless um and so again that's just a qualitative observation about this particular gas and so that would be a description of a physical property and so lots of other physical or other physical properties include um yeah the the the the color um the shape uh the smell so things that do not have to do with any kind of actual chemical change for b we have apple slices turn brown when they are exposed to air so now in this circumstance um we have a visual color change and what that indicates to us is that some chemical process is taking place so that is a chemical property so c we have that phosphorus will ignite when exposed to air so what this observation is describing is a a chemical reaction that phosphorus will undergo if it is exposed to air so again this is a chemical property at room temperature mercury is a liquid um so again this is just a qualitative observation right if we have a sample of mercury we can say that it's very silver it is a liquid at room temperature so again no chemical change is occurring so that is a physical property and for e we have that propane gas is compressed to a liquid for placement in a small cylinder so in this um instance we are talking about if we have some sample of propane gas right and we compress it down so that it turns into a liquid well then what we end up having is just a liquid propane as opposed to gaseous propane um so chemically the propane itself has not been changed it's just undergone a phase change from a gas to a liquid but again it's not fundamentally you know chemically altered in any way so this and so this phase change and other phase changes between these different phases of matter are all physical changes and physical properties and so then we'll explore this idea further in 3.12 what type of change physical or chemical takes place in each of the following so for a we have that pie dough is rolled into thin pieces for a crust so again if if we if we take our our pie dough and we just use our roller to roll it out and then um you know cut it up or what have you uh we're not chemically altering the pie dough in any way um we're just we're just rolling it up into a different shape so this would be a physical property all right for b we have a silver pin tarnishes in the air um so this is similar to the um example that we saw uh earlier where we had phosphorus will ignite if it's exposed to air um certainly this isn't an example of something being ignited but it is another example of some substance that is uh reacting with air and so this is very common for metallic substances where they become oxidized when they are exposed to air and they form this thin oxide layer on the outside so this is a chemical reaction where what was formerly just a solid piece of pure metal then reacts uh with air and forms an oxide layer on the outside so this is a chemical property for c a tree is cut into boards at a saw mill so again if we are just taking some substance and we are chopping it up cutting it up at our sawmill we are not chemically altering the wood itself we're just we're just changing it's it's shape and size so this would be another physical property for d we have food is digested um well um certainly you know once we uh consume food and it goes into our stomach we know we have various enzymes and stomach acid that works on the food to to break it down so that would be a chemical process occurring inside of us so the process of digestion processes those are all chemical properties and then for e we have that a chocolate bar melts um so um again this is a phase change where we have a a solid chocolate bar is is melting into ooey gooey oozy chocolate but the chocolate itself is not altered chemically um if the the composition of the molecules remains unchanged it just has undergone a phase transition so this would be a physical property excuse me um so um that that's basically it for 3.2 um chemical and physical properties you know as i mentioned the question to ask yourself is is this substance fundamentally different um after um you know after this observation um or this change has has occurred and again if it's just a phase change solid to liquid uh gas to liquid et cetera um this com the the substance is not chemically altered it's just undergone a phase transition which is really just kind of a rearrangement of the molecules so all of that being physical but yeah okay 3.2