what's going on besie today we're going to be talking about the te's version 7 science portion of the exam more specifically chemistry and we're going to be highlighting properties of solution let's get started so water is truly a remarkable molecule it's not just an essential when it comes to life but it's because of its unique properties that makes it crucial for biological functions one of the key features when it comes to water is its structure and polarity water molecules are shaped in such a way that the oxygen atoms which are highly electr negative tends to attract more electrons towards itself compared to the hydrogen ions that it's bonded with oxygen and hydrogen form calent bonds as we discussed in our atomic structure video oxygen with an atomic number of eight has eight protons and eight electrons two in its inner shell and six in its outer shell it needs two more electrons to complete its outer shell based on that octet rule it gets these electrons when two hydrogen atoms which both have one veence electron in the outer shell share with oxygen this uneven distribution of electrons gives oxygen a slightly more negative charge and hydrogens a slightly more positive charge this polarity allows water molecules to easily bond with each other the slightly negative oxygen of one molecule can attract the slightly positive hydrogen of another forming a hydrogen bond these bonds are what gives water its special properties such as its ability to dissolve many substances its surface tension and its relatively high boiling point compared to other molecules of similar size have you ever observed how water sticks to the side of a glass and wondered how does water stick to a glass without falling down does it defy gravity what's particularly interesting about water is its ability to adhere to the walls or surfaces of objects a phenomenon known as adhesion which assists in countering gravity pole furthermore water molecules form hydrogen bonds amongst themselves this process is called cohesion for this I want you to picture water droplets on a waxed car's surface they tend to beat up because they prefer sticking to each other rather than spreading out all over the surface of the car additionally cohesion explains exp why water striders those little bugs which are my favorite insects by the way can ously move across the surface of a pond or a stream without actually having to go into the water this is because cohesion enhances the surface tension of water enabling these little bugs to skate across it without sinking so here's the key difference between these two concepts when it comes to adhesion we have water molecules that are attracted to dissimilar objects meaning they're attracted to something else besides themselves whereas with Co cohesion there attraction is going to take place between the water molecules themselves so cohesion they're going to be co-working together that's your memory trick cooworker c-ome they like to stick to each other right they're at home when they're with each other whereas adhesion is they're sticking to dissimilar things things that are not water so I like to think of it as adhesive tape where Modern molecules are like sticky objects like we see with adhesive tapes when it comes to sticking to walls or different surfaces so let's talk about another important concept when it comes to the teas and that is solute solvent and solutions so let's begin by exploring what constitutes a solution with a simple experiment involving three different glasses of water in the first glass we're going to add salt in our second glass we're going to add sugar and in our third glass we're going to add Pebbles after allowing some time for these examples to interact with water we're going to observe the following the salt is going to completely dissolve forming what we know as a homogeneous mixture this means that the mixture is going to have a uniform composition and with looking with just our naked eye we're not going to be able to differentiate between the salt particles and the water just like with our salt sugar is also going to dissolve completely in the water resulting in another homogeneous mixture we're also not going to be able to differentiate between the sugar particles and the water itself so again it's going to have a uniform composition however unlike salt and sugar the sand or Pebbles that we put in our last water is not going to dissolve this results in what we know as a heterogeneous mixture where the individual particles of sand or Pebbles are going to remain visible and distinct from the water from these observations we can conclude that both the salt water and sugar water mixtures are solutions because they consist of substances both salt and sugar that are soluble in water forming homogeneous mixtures on the other hand the mixture of Pebbles and water is not a solution due to its heterogeneous nature in which the substances remain visible to the eye thus a solution is defined as a homogeneous mixture of one or more solutes where the components are completely dissolved in a solvent leaving no visible trace of Separation to the naked eye so here are some common examples of solution ions to illustrate this concept when we're looking at cold drinks we have a combination of carbon dioxide sugar flavors as well as water when mixed together they form a homogeneous mixture this means all components are evenly distributed throughout the drink making it a solution in the case of fog and clouds water Vapors are dissolved in air making it a homogeneous mixture and lastly when alcohol is mixed into water it dissolves completely resulting in our last homogeneous mixture the uniform distribution of alcohol molecules within the water makes us a classic example of a solution all three of these examples represent Solutions where the solute is completely dissolved in the solvent creating a uniform mixture without any visible separation of components let's dive into solutes and solvents by examining a salt solution and a sugar solution in both cases these Solutions consist of two components salt and water in the salt solution and sugar and water in the sugar solution as we discussed before both salt and sugar can be dissolved in water and present in smaller quantities compared to the water itself therefore we Define a solute as a component of a solution that can be dissolved and is present in smaller amounts conversely a solvent is defined as its ability to dissolve substances and is present in larger amounts so this makes sense in our example right we have built salt and sugar which are smaller amounts making them our solutes and both water in both cases is going to be our solvent cuz it's going to be present in larger amounts an easy way to remember the differences is sugar water syrup where our solute is sugar our solvent is water and our solution is syrup it's also easy to recall that as we move down our list of definitions our number of characters in each word is going to increase solute has six characters Sal vent has seven characters and solution has eight here are some more common examples of solutes and solvents in a vinegar solution we can see that acidic acid is going to be our solute it's a much smaller number and our water is going to be our solvent because it's in Greater quantity moving down the line we have sugar and milk sugar is going to be our solute and milk is going to be our solvent and then with alcohol and water again alcohol is going to be our solute and water is going to be our solvent if you haven't been able to pick up on it yet water is often hailed as the universal solvent because of its exceptional ability to dissolve a wide variety of substances particularly polar substances polar substances such as salt which is sodium chloride and sugar which is sucrose dissolve well in water this is due to the partial charges on their molecules which attract the partial charges on water molecules thus facilitating solution conversely we have non-polar substances like we see with oils and fats which often struggle to dissolve in water their molecules lack charged regions which are necessary to effectively interact with water molecules therefore although water can dissolve numerous types of substances it is predominantly effective with polar substances earning its reputation as the universal solvent additionally when preparing for your atits you're going to come across two important terms hydrophilic and hydrophobic hydrophobic means water fearing or water hating and it describes substances that do not dissolve well in water and tend to repel it this category includes oils fats as well as other non-polar molecules examples of hydrophobic materials in daily use could be waterproof Fabrics which are treated to repel water hydrophilic means water loving and it refers to substances that dissolve readily in water this includes polar substances and molecules like ionic compounds such as salt and polar molecules such as alcohol many beverage ingredients are hydrophilic allowing them to dissolve in water because water itself is a polar molecule hydrophilic substances can disintegrate and become encased in water molecules which AIDS in their dissolution so let's discuss marity a term frequently used when discussing Solutions we often refer to a substance's concentration rather than simply counting its moles the concentration tells us the number of moles of a substance present per unit volume the unit of measure for concentration and marity is expressed as moles of a solute per liter of solution and is denoted by the capital M for instance a solution with a marity of 2 m contains 2 moles of solute for every liter of solution we can change the concentration of a solution through the process of delution which involves adding more solvent to the solution as a result if the number of moles of solute remains constant then the solution becomes less concentrated because of the overall volume increase to calculate the new concentration after dilution we use a specific calculation that requires the initial concentration the initial volume and the final volume to which the solution will be diluted these quantities are inversely related meaning that if you double the volume of the solution the concentration will be haved so let's take a look at an example we have calculate the marity of a solution prepared by dissolving 9.8 moles of a solid NaOH in enough water to make 3.62 L of solution so we know what our moles are and we know what our solution is in liters so we just go ahead and we plug that into our marity equation so we have m is equal to 9.8 moles over 3.62 l and we're just going to divide and that's going to give us a marity of 2.7 moles per liter so let's take a look at a more complex problem so we have 0.850 l in a 5m solution of sodium chloride is diluted to a volume of 1.8 L so we have our original volume and our new volume here with water what is the concentration of the diluted solution so we start with our equation we have M1 multipli by V1 is equal to M2 multipli by V2 so that's just your first moles your first volume your second moles your second volume so here we need to figure out what our second moles is if we dilute the solution with 1.8 L so I'm going to go ahead and put that on the left side of my equal sign and I'm going to multiply my first solution which is our M1 V1 and I'm going to divide that by what we added for the dilution of our second solution so we're just going to go ahead and plug in our numbers so we have 5m is multiplied by 0.85 L this is our first solution and it's going to be divided by what we have added to dilute the solution of 1.80 L if we do our calculations correctly we should see that the marity the moles that we see in our second solution is now going to be 2.36 moles osmosis is a term that is often mentioned but can be quite complex to grasp however understanding it can clarify numerous important questions that you may have such as why is it harmful to administer an IV of pure water or what happens when a saltwater fish is placed in fresh water we'll explore the answers to these questions while explaining the process of osmosis when we're discussing osmosis we're referring to how water molecules move through a semi-permeable membrane such as a cell membrane due to their small size water molecules can pass through the membrane uned or if we have a large quantity of water molecules they can move through a specialized protein Channel known as an aquaporin this transport of water molecules across the cell membrane is considered a passive transport meaning that it doesn't require any energy in order to get across water molecules naturally migrate from areas where their concentration is high to where their concentration is low another to consider this movement is to consider solute concentration a region where a low water concentration generally means that we're going to see a higher concentration of solutes like salt and sugars since these solutes are dissolved in a solvent like water the water will tend to move towards areas with higher solute concentrations which correspondingly have lower water concentrations thus if you're trying to predict the direction of water molecules in osmosis simply look for concentrations that have greater solutes in the absence of other influences like pressure water is going to continuously move towards the area of higher solute concentrations an easy way that I like to remember osmosis is to think of H2O and O and osmosis and this means that it's going to be the movement of water so let's introduce what is known as the YouTube setup yes it's a little bit like YouTube the platform but it's a little bit more scientific in the middle of our YouTube we're going to have semi per perable membranes similar to a cell membrane which allows small water molecules to pass through but blocks large molecules like salt initially when we take a look at our first example we can see that both side a and side B are filled with equal levels of water while it may appear nothing is happening water molecules are constantly in motion however the net movement between the two sides is zero meaning there's no overall change in the direction of the water movement so let's add a twist suppose we add a significant amount of salt to side B given what we know about osmosis in which direction do you think the water is going to move side a or side B and you're absolutely correct it is side b side B now has a higher solute concentration compared to side a water naturally moves towards area with higher solute concentrations which also means that we're going to see a lower water concentration on that side consequently the water level on side B is going to rise as water attempts to move to dilute and equalize that concentration on both sides once equilibrium is achieved that net movement of water across the membrane will stop yet the water molecules will continue to move back and forth dynamically this continuent movement reflects the natural kinetic behavior of water molecules always seeking to balance and redistribute themselves here's a key term that you're going to need to remember side B is going to be the described as hypertonic this means that it has a higher solute concentration however it's important to note that calling something hypertonic always involves a comparison so in this case we can say that side B is hypertonic relative to side a because it contains more solutes than we see in side a we can also refer to side a as hypotonic the pneumonic hypo rhymes with low hypol low and this can help you remember hypotonic area is having a lower solute concentration compared to their counterparts so now let's apply these Concepts beyond the YouTube experiment and into more real life practical scenarios when someone receives an IV at a hospital the fluid in the IV might appear to be pure water but in reality it's definitely not using pure water would be extremely harmful because of Osmosis let's consider why let's imagine that hypothetically the pure water was used in an IV this IV tube typically runs into the vein providing direct access to the bloodstream which is crucial for medication administration your blood contains various components including red blood cells now let's consider solute concentrations between the hypothetical pure water of an IV and your red blood cells which one has the higher solute concentration since cells are not empty but do contain various solutes and the hypothetical pure water has none the solute concentration inside the red blood cell is going to be higher due to osmosis water moves from the low solute concentration in the IV which we see with pure water towards the higher concentration inside of ourselves as a result the red blood cells which are hypertonic compared to the pure water is going to rush into this cell and it's going to cause that cell to start to swell and become full of water and potentially even bursting which could be really bad for the organism when when a person requires hydration through an IV they're usually given a solution that is isotonic to their body and their plasma isotonic means that the solution is equal in concentrations of solutes to the plasma preventing that osmotic imbalance therefore there will be no swelling or shrinking of red Bal cells ensuring their normal function is maintained hypertonic means that these Solutions have higher concentrations of solutes compared to another solution an easy way that I like to remember this is hyper rhymes with higher hyper higher because there's going to be a higher solute imbalance when it comes to hypertonic Solutions we're going to see water coming out of our red blood cells because its outside environment solutes are going to be greater than the solutes found within the cells so as we know with osmosis osmosis the water is going to go from a lower concentration to a higher concentration in order to even it out so you're going to see shell cell shrinking whenever we're talking about hypertonic solution because of that lack of water conversely hypotonic solution refers to a lower concentration of solutes compared to other Solutions and an easy way that I like to remember this is hypo means low it just it Rhymes and it makes it easy to remember so because the solution has less solutes than we're going to find inside of our red blood cells the same thing is going to happen with osmosis it's going to want to move towards these cells with a higher concentration and because of this it's going to cause the red blood cells to ultimately swell up and potentially burst depending on how imbalanced those solutes are so when you're trying to figure out which kind of solution is isotonic hypertonic or hypotonic this is an easy way that I like to remember it the two solutions that you're going to see commonly with isotonic is going to be your normal saline 0.9 uh% as well as your lactated ringers if you're looking at hypertonic hyper meaning higher you're going to see a lot higher numbers you're going to see three 3% to 5% saline 10% dextrose in water 5% dextrose in normal saline or half normal saling you're going to even see 5% Dex stros in uh lactated ringers so you're going to see higher percentages meaning that there's higher solutes in contrast where we're talking about hypotonic solution hypo meaning low you're going to see lower concentrations right so you're going to see half normal saline you're going to see 0.225 per normal saline and 0.33% % normal saline next up let's talk about diffusion which refers to the process where the net movement of a substance moves down its concentration gradient traveling from an area of high concentration to one of a low concentration so the big key difference here when we compare to osmosis is osmosis is referring to the water we're talking about the solvent whereas now we're talking about the movement of particles not the movement of water so we're talking about the solutes so that's why it's going to be a little bit different from what we were talking about with osmosis what's important to note that this process isn't limited to liquids it can also refer to Gases such as air fresheners when they're sprayed up into the air the molecules of an air freshener spread from where they are most concentrated to where they are less concentrated allowing the scent to be detected even from a distance let's also delve into some key points when it comes to diffusion the first term being net movement which refers to the overall direction of the molecule movement diffusion doesn't prevent molecules from moving in the opposite direction nor does it imply that the molecular movement ceases all together even when equilibrium is reached where the concentration of molecules is equal throughout the space the molecules continue to move around just like we saw with osmosis secondly diffusion is a type of passive transport meaning that it doesn't require any external energy to occur molecules move due to the inherent potential energy present in the concentration gradient itself this is why the diffusion of a substance Like Oxygen into cells is considered passive transport no additional energy is required for this to happen passive transport is distinct from processes like active transport which requires energy input before we move on to that we have one specific type of diffusion known as facilitated diffusion this process still involves the net movement of molecules from an area of higher concentration to an area of lower concentration however certain molecules may be too large or possess other characteristics that prevent them from crossing the cell membrane itself in such cases these molecules have to pass through a protein Channel this is still considered diffusion because it's a form of passive transport and the molecules continue to move along their concentration gradients the key difference is that facilitated diffusion requires the presence of a protein channel to assist the molecule in entering the cell let's talk about several factors that can influence the rate of diffusion so number one we have distance so the further the molecule has to travel the slower the diffusion rate for instance diffusion might occur at different rates in 5 ft compared to 5 miles due to the increased distance the molecule must travel next up we have temperature so quick question do you think a higher or lower temperature would increase the diffusion rate assuming all other Factor factors are going to remain the same you're right generally higher temperatures are going to increase the diffusion rate this is because the molecules move more rapidly at higher temperatures enhancing their energy which in turn speeds up diffusion next up we have solvent characteristics which just means that the density of a solvent can also impact diffusion the denser a solvent is might impede molecular movement thereby reducing the diffusion rate and then we have traveling characteristics not all entities involved in diffusion are strictly molecules there can be other types of substances as well for example the mass of a diffusing substance plays a critical role typically substances with greater masses diffuse slower than those with less Mass due to their inertia and then lastly we have barrier characteristics if a diffusion involves crossing a barrier such as a cell membrane the nature of the barrier significantly affects the rate of diffusion small non-polar substances generally pass through cell membranes more easily than those with larger more polar substances influencing the overall rate of diffusion so we talked about passive Transportation when it comes to diffusion facilitated diffusion and osmosis you should know one more additional mode of Transport when it comes to the aits and that is active transport active transport is a critical cellular process where molecules are are transported against their concentration gradient moving from areas of lower concentration to areas of higher concentration unlike passive transport which allows molecules to move along the gradient without using energy active transport requires the cells to expend that energy in order to make that happen this energy is typically provided in the form of ATP also known as adenosine triphosphate the cell's primary energy currency in active transport cells use specialized protein channels embedded in the cell's membrane known as Transporters or pumps these proteins bind to the molecules they are designed to transport changing shape with the energy derived from ATP to move these molecules across the cell membrane this process is vital for maintaining essential functions such as nutrient uptake waste removal and ion balance within the cell active transport is not only crucial when it comes to individual cells it is also pivotal when it comes to physiological processes across organisms for example it helps with the accumulation of nutrients across a concentration gradient like we see in our intestines and with the reabsorption of ions that we see within our kidneys by understanding active transport researchers and medical professionals can better comprehend cellular and systemic functions potentially leading to improved treatments for various health conditions where transport processes can be disrupted I hope this video was helpful in understanding properties of solutions if you have any questions make sure that you leave them down below I love answering your questions head over to nurse chunk store.com where there is a ton of additional resources to help you pass those ait's exams and as always I'm going to catch you in the next video bye