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hi it's mr. Andersen and this is chemistry essentials video 15 which is

Hi. It's Mr. Andersen and this is chemistry essentials video 15, which is

on solutions we generally think of solutions as being liquids like this

on solutions. We generally think of solutions as being liquids, like this beverage right

beverage right here but remember solutions could also be made of gases like air and then we could also have

here. But remember solutions could also be made of gases, like air. And then we could

solids that are solutions so steel is an example of that we have carbon atoms

also have solids that are solutions. So steel is an example of that. We have carbon atoms

inside these iron atoms and so a solution remember is going to be made of

inside these iron atoms. And so a solution remember is going to be made of two things.

two things solvent and solute solutes are going to be dissolved within the solvent and generally we're going to

Solvent and solute. Solutes are going to be dissolved within the solvent. And generally

have more of the solvent than the solute this should be homogeneous in nature

we're going to have more of the solvent then the solute. They should be homogenous in nature.

that means they're going to be smooth throughout the whole we can't see

That means they're going to be smooth throughout the whole. We can't see different parts or

different parts or different concentrations in various areas this is based on scale obviously if we look at

different concentrations in various areas. This is based on scale. Obviously if we look

the molecular level nothing is going to be smooth and so what we usually use is

at the molecular level, nothing is going to be smooth. And so what we usually use is the

the human eye if we if it looks homogeneous to the human eye we're going

human eye. If it looks homogenous to the human eye we're going to call it a solution. That's

to call it a solution that's one of the indicators it could be made of liquid solids and gases and if we have a liquid

one of the indicators. It could be made of liquids, solids and gases. And if we have

solution we could have solids and gases dissolved within it and so generally

a liquid solution we could have solids and gases dissolved within it. And so generally

we're talking about liquids when we're talking about solutions so what are some properties does it scatter light we'd

we're talking about liquids when we're talking about solutions. So what are some properties?

have to put a big no there if it

Does it scatter light? We'd have to put a big no there. If it scatters light it's not

scatters light it's not going to be a solution how do we separate the solute how do we get it out of this solution

going to be a solution. How do we separate the solute? How do we get it out of this solution?

could we run it through a filter no we can't filter it it's going to run right

Could we run it through a filter? No. We can't filter it. It's going to run right through

through a filter and so we have to have another way to get those solutes out one

a filter. And so we have to have another way to get those solutes out. One way would be

way would be through a process called chromatography and what we're looking at

through a process called chromatography. And what we're looking at is the different intermolecular

is the different intermolecular forces between the solutes and we're using that to separate them and then we could also

forces between the solutes. And we're using that to separate them. And then we could also

use distillation that also is looking at intermolecular forces but we're looking

use distillation. That also is looking at intermolecular forces. But we're looking at

at differences in vapor pressure to separate them and so those are two ways

differences in vapor pressure to separate them. And so those are two ways that we can

that we can separate the solutes from solvent when they form that formation of

separate the solutes from the solvent. When they form, that formation of a solution could

a solution could either be exothermic so it's releasing heat or endothermic words can zooming heat and that's all based on

either be exothermic, so it's releasing heat. Or endothermic, where it's consuming heat.

intermolecular forces as well and then

And that's all based on intermolecular forces as well. And then finally the composition

finally the composition of a solution we're going to measure that in molarity which is going to be the moles of the

of a solution. We're going to measure that in molarity, which is going to be the moles

solute in the leaders of the solution and in chemistry you should be able to

of the solute in the liters of the solution. And in chemistry you should be able to prepare

prepare a basic molar so and so remember solutions could be solids liquids gases it has to hit these

a basic molar solution. And so remember solutions could be solids, liquids, gases. It has to

three things it has to be homogeneous to the naked eye it can't scatter light and

hit these three things. It has to be homogenous to the naked eye. It can't scatter light.

then finally it cannot be filtered and if it hits all of those it's probably

And then finally it can not be filtered. And if it hits all of those, it's probably going

going to be a solution we can't filter it remember so how are

to be a solution. We can't filter it remember so how are we going to separate the different

we going to separate the different parts of it well one of these two processes either chromatography and distillation both of

parts of it? Well one of these two processes. Either chromatography or distillation. Both

them use intermolecular forces so the forces between the solutes and the

of them use intermolecular forces. So the forces between the solutes and the forces

forces between the solute and the solvent itself so basic chromatography

between the solute and the solvent itself. So basic chromatography is just using these

is just using these interactions but if we were to heat them up eventually some

interactions. But if we were to heat them up, eventually some of them are going to move

of them are going to move from a liquid into us into a gas phase and so that's going to increase the vapor pressure and

from a liquid into a gas phase. And so that's going to increase the vapor pressure. And

so distillation is going to use differences in this vapor pressure to

so distillation is going to use differences in this vapor pressure to separate. So for

separate so for example this might be alcohol it has a high vapor pressure that means it easily is going to

example this might be alcohol. It has a high vapor pressure. That means it easily is going

evaporate so we could use that to separate so chromatography comes in two

to evaporate so we can use that to separate it. So chromatography comes in two different

different types we could either either have paper chromatography or column chromatography in paper chromatography

types. We could either have paper chromatography or column chromatography. In paper chromatography,

what we do is we take our solution so a great example we use in a biology class

what we do is we take our solution. And so a great example we use in biology class is

is we'll mash up leaves we filter the material inside the leaf and then we

we'll mash up leaves. We filter the material inside the leaf and then we want to separate

want to separate it into the different pigments that are found within the leaf and so what we'll do is put that in some

it into the different pigments that are found within the leaf. And so what we'll do is put

kind of a solution will generally dissolve it in some kind of an alcohol

that in some kind of a solution. We'll generally dissolve it in some kind of an alcohol. And

and then we just have paper and we'll put the paper inside that solution and

then we just have paper. And we'll put the paper inside that solution. And what happens

what happens over time is it's going to migrate up we're going to have a front

over time is it's going to migrate up. We're going to have a front that migrates up. And

that migrates up and eventually what we can do is separate that all into its

eventually what we can do is separate that all into its different solutes. Some of these

different solutes some of these would be like chlorophyll and so how does that work well it's based on intermolecular

would be like chlorophyll. And so how does that work? Well, it's based on intermolecular

connections and so it's based on how well these solutes adhere to the solvent

connections. And so it's based on how well these solutes adhere to the solvent that they're

that they're dissolved in because if they really love the solvent they're

dissolved in. Because if they really love the solvent they're going to be pulled all

going to be pulled all the way to the top and also how much do they adhere to

the way to the top. And also how much did they adhere to the paper. And so it's the

the paper and so it's the sum of all these connections that allow us to separate them apart column

sum of all of these connections that allow us to separate them apart. Column chromatography

chromatography is going to work in a little bit different way what we'll use

is going to work in a little bit different way. What we'll use is a big column. So it's

is a big column so it's going to be a big glass column and it's going to have a exit point at the bottom we're going

going to be a big glass column. And it's going to have an exit point at the bottom. We're

to put some absorbent inside there usually that's going to be like a silica

going to put some absorbent inside there. Usually that's going to be like a silica gel.

gel and then we'll put some aluminum oxide inside it so we have the absorbent

And then we'll put some aluminum oxide inside it. So we have the absorbent in there. And

in there and then we're simply going to dump our solution up at the pop and timing is important when we're

then we're simply going to dump our solution up at the top. And timing is important when

doing column chromatography what's going

we're doing column chromatography. What's going to happen in here is that we have two

to happen in here is that we have two different solutes dissolved in that one solution so as we let it run they're

different solutes dissolved in that one solution. So as we let it run, they're going to move

going to move down the column at different rates why is that well let's say a is not adhering to the absorbent

down the column at different rates. Why is that? Well let's say A is not adhering to

as much as the red is the blue is not going to adhere to the absorbent as much

the absorbent as much as the red is. The blue is not going to adhere to the absorbent as

as the red is and so it's quickly going to move through there

much as the red is. And so it's quickly going to move through there. And so what we can

and so what we can do is we can collect that first solute and then we can move it over and we can connect this second

do is we can collect that first solute. And then we can move it over and we can collect

solute we're still looking at these intermolecular forces we're just doing

the second solute. We're still looking at these intermolecular forces. We're just doing

it in a slightly different way distillation works in a different way

it in a slightly different way. Distillation works in a different way. Distillation, what

distillation what we're looking at is differences in vapor pressure and we've been distilling for a long time humans

we're looking at is differences in vapor pressure. And we've been distilling for a long time.

have so example we could take wine and we could put wine in here and what's

Humans have. So an example, we could take wine and we could put wine in here. And what's

going to happen is the alcohol is going to evaporate so it's going to evaporate

going to happen is the alcohol is going to evaporate. So it's going to evaporate, turn

turn into a gas phase we have condensers up here and then it's going to turn it

into a gas phase. We have condensers up here. And then it's going to turn it into a liquid

into a liquid phase over here and so since there excuse me since they're

phase over here. And so since they're, excuse me, since they're going to have different

going to have different vapor pressures ones that are more volatile ones that have a higher vapor pressure that are

vapor pressures, ones that are more volatile, ones that have a higher vapor pressure that

going to evaporate more quickly are going to separate off where do we use

are going to evaporate more quickly, are going to separate off. Where do we use this distillation

this distillation process inside aside from making brandy out of wine we'd use it in oil refining for example to get

process, aside from making brandy out of wine? We'd use it in oil refining for example, to

the different parts out of crude oil ionic compounds are important in

get the different parts out of crude oil. Ionic compounds are important in solutions

solutions as well and so in this simulation what I'm going to do is I'm

as well. And so in this simulation what I'm going to do is I'm going to take some salt

going to take some salt and add it to water and so as we add salt to water first of all water by itself doesn't

and add it to water. And so as we add salt to water, first of all water by itself doesn't

connect electricity and so what we'll do is shake a little bit of salt in there

conduct electricity. And so what we'll do is shake a little bit of salt in there. And

and then we could use a conductivity measure to figure out okay now we're

then we could use a conductivity measure to figure out, okay, now we're transmitting a

transmitting a little bit of energy let's say we add a little bit of salt to

little bit of energy. Let's say we add a little bit of salt to it. What's going to happen

it what's going to happen to the conductivity it's going to increase you can also see in the upper right that

to the conductivity? It's going to increase. You can also see in the upper right that we're

we're increasing the concentration of that salt but now let's evaporate some of that

increasing the concentration of that salt. But now let's evaporate some of that water.

water so as the water evaporates look at the concentration it's increasing and

So as the water evaporates, look at the concentration. It's increasing. And then right at the end

then right at the end we just have a layer of salt at the bottom let's look at the microscopic level so sodium

we just have a layer of salt at the bottom. Let's look at the microscopic levels. So sodium

chloride remember is an ionic compound and so as we add that to salt it's going

chloride remember is an ionic compound. And so as we add that to water it's going to separate

to separate into its both sodium and chloride ions and so they're each going

into both sodium and chloride ions. And so they're each going to dissolve in the water.

to dissolve in the water as we remove the water again what happens the concentration increases and then bang

As we remove the water again, what happens? The concentration increases. And then bang

we're back this ionic compound again what's going on at the molecular level well let's

we're back to this ionic compound again. What's going on at the molecular level, we'll let's

watch if we add the sodium chloride to the water it's going to break apart into

watch. If we add the sodium chloride to the water, it's going to break apart into its

its ions the sodium which are positive are going to be attracted to the pot to

ions. The sodium which are positive are going to be attracted to the negative ends of the

the negative ends of the water you can see the negative ends of the water are going to be adjacent to the sodium and

water. You could say the negative ends of the water are going to be adjacent to the

then the positive parts of the water are going to be adjacent to the chloride

sodium. And then the positive parts of the water are going to be adjacent to the chloride

ions and so it's really easy to take something like water which is a clear

ions. And so it's really easy to take something like water, which is a clear dipole, and we

dipole and we could absorb ions with it formation of those solids is going to

could absorb ions with it. Formation of those solids is going to either take in energy or

either take in energy or release energy and so what we can look at is the formation of a solid these are going to

release energy. And so what we can look at is the formation of a solid. These are going

be the enthalpies of that solution some are positive some are negative and so if

to be the enthalpies of that solution. Some are positive. Some are negative. And so if

we were to look at these ones imodium nitrate if we add that to water

we were to look at these ones, ammonium nitrate, if we were to add that one to water, it's

it's going to be an endothermic process that means it's going to take in energy

going to be an endothermic process. That means it's going to take in energy. And so we could

and so we could use that ammonium nitrate in water to make these instant

use that, ammonium nitrate and water to make these instant cold packs. What we're doing

cold packs what we're doing is just combining them together it's taking in

is just combining them together. It's taking in heat from the surroundings and it feels

heat from the surroundings and it feels really really cold a lot of these are going to be exothermic so when you mix

really, really cold. A lot of these are going to be exothermic. So when we mix them with

them with water it's going to release energy and all of this has to do with intermolecular forces an example of this

water it's going to release energy. And all of this has to do with intermolecular forces.

could be hydrochloric acid hydrochloric acid when you mix it with water is going

An example of this could be hydrochloric acid. Hydrochloric acid, when you mix it with water

to create a huge amount of heat if you were to have a huge amount of

is going to create a huge amount of heat. If you were to have a huge amount of hydrochloric

hydrochloric acid just dump a little water in there you'd have this massive

acid and just dump a little water in there, you'd have this massive reaction. Huge amount

reaction huge amount of heat and that's why in the chemistry lab we always add acid small limits small amounts of acid

of heat. And that's why in the chemistry lab we always add acid, small amounts of acid

to the water because it's going to generate heat and that water is able to

to the water. Because it's going to generate heat and that water is able to mediate some

mediate some of that change remember we measure the concentration of a solution using molarity which is going

of that change. Remember we measure the concentration of a solution using molarity, which is going

to be the mall moles of solute in liters of total solution and let's say you're

to be the moles of solute in liters of total solution. And let's say you're doing a lab

doing a lab and they say prepare a point five molar sodium chloride solution or

and they say prepare a 0.5 molar sodium chloride solution or salt solution. How would you do

salt solution how would you do that well they're already telling you how many moles you're going to put into the

that? Well they're already telling you how many moles you're going to put into the solution.

solution they're saying point five moles of sodium chloride so we have to convert

They're saying 0.5 moles of sodium chloride. So we have to convert that to a mass, something

that to a mass something that we can actually deal with so we're going to use this conversion to convert that to grams

that we can actually deal with. So we're going to use this conversion to convert that to

where are we getting this 58.4 for we're using the atomic weight of both sodium

grams. Where are we getting this 58.44? We're using the atomic weight of both sodium and

and chlorine we're then going to make that conversion and that's going to be twenty nine point two two grams so what

chlorine. We're then going to make that conversion. And that's going to be 29.22 grams. So what

would we do in an Erlenmeyer flask we could add a certain amount of water then

would we do in an Erlenmeyer flask, we could add a certain amount of water. Then we're

we're going to add our salt to it we're going to make sure it dissolves and then

going to add our salt to it. We're going to make sure it dissolves. And then we're going

we're going to bring that volume up to one liter to make that point five molar sodium chloride solution so did you

to bring that volume up to 1 liter to make that 0.5 molar sodium chloride solution. So

learn the following two separate solutes we could use chromatography both paper

did you learn the following? To separate solutes we could use chromatography, both paper and

and column and that's going to be based on intermolecular forces did you figure out how to use representations show the

column. And that's going to be based on intermolecular forces. Did you figure out how to use representations

interactions between them remember if we look at that molecular level we were

to show the interactions between them? Remember if we look at that molecular level, we were able

able to show how water is able to dissolve these ionic or these ions were we able to use representations to link

to show how water is able to dissolve these ions. We're we able to use representations

molarity to particle view and so we were able to do that and also kind of

to link molarity to particle view? And so we were able to do that and also kind of calculate

calculate a certain molar solution and then finally could we design something like a distillation process where we

a certain molar solution. And then finally, could we design something like a distillation

could separate solutes yeah we just have

process where we could separate solutes? Yeah. We just have to look at their different vapor

to look at their different vapor pressures to pulling apart those are solutions and I hope that was helpful

pressures to pull them apart. Those are solutions and I hope that was helpful.