2 Solutions are special kinds of mixtures Let’s review!!Element – pure substancehomogeneous throughoutonly one kind of matter presentCompound – pure substancehomogenous throughoutmade from 2 or more elementschemical in natureMixture – can be homogeneous or heterogeneousmade from 2 or more elements, compounds, or bothphysical in nature
3 Because solutions are mixtures they have two parts: solutes thing being dissolvedmost often a solid, but can be any statethink: SODAsolvents thing doing the dissolvingmost often a liquid – water for instance – but can be any statethink: our atmosphere – NITROGENDissolving does not mean a change in state. Solutes do not melt! They remain a solid (if they are a solid to begin with)
4 The charge of the nucleus Is felt making it feel positive Polarity – the uneven distribution of charges on a moleculeuneven distribution is a result of:a. Sharing of electrons between atoms with different energy1. Asymmetric molecules are polarElectrons are veryPresent on this sideOf the moleculeThat makes this sideOr pole of the moleculeFeel negativeThis side or pole of theMolecule has noElectrons present.The charge of the nucleusIs felt making it feelpositiveHydrogen has one electron on the K shellFluorine has 9 electrons on the K and L shells. Fluorine is a larger atom withMore energy. F controls all of the electrons.
5 In the water molecule, hydrogen is a smaller atom with less energy than oxygen.When the electrons are share between these two atoms,oxygen controls the electrons because it is an atom with more energy.Because of this the molecule has two poles – one that feels positive(hydrogen’s end) and the other that feels negative (oxygen’s end).
6 Molecules can also be nonpolar – an even distribution of charge on the molecule. a. Sharing of electrons between atoms of equal energy1. DiatomsHere this diatom, electrons are on the same energy level. Electrons are on the sameenergy shells and therefore are controlled equally by each atom. Electrons spinequally around each nucleus.
8 Well how does all this connect with solutions Well how does all this connect with solutions? The reason why solutes stay in solutionis because of polarity. Polar solutes dissolve most easily in polar solvents – water is polarand so it can dissolve all polar molecules. Nonpolar solvents dissolve nonpolar solutes.NaClCl -Cl -Na +Na +Cl -Cl -Cl -Na +Na +Na +Cl -Na +Na +Cl -NaCl is an ionic compoundthat is made up of + Naions and - Cl ions.NaClWhen an ionic compounddissolves in water it iscalled DISSOCIATION.Cl -Cl -Na +Cl -Na +Na +Na +Na +Cl -Cl -Cl -Na +Cl -Cl -Cl -Cl -Cl -Na +Cl -Na +Na +Cl -Na +
9 If a non polar molecule is put into water, it will NOT dissolve because of the like Charges that will meet in the water and the solute.CH4 is a symmetricmolecule that isnon polar. It will notdissolve in waterbecause it will be repelledby the positive pole ofthe water molecule.
10 Solubility – the ability of a solvent to dissolve a solute. Solubility will be affected by:pressuretemperatureparticle size – the smaller the particles of solutethe easier it will fit into thespaces of the solvent.stirring – moving the solute around pushesparticles into solution.Affects molecular distance of solvent.The larger the MD, the more solute thatcan be dissolved, and vice versa.
14 There exists two types of solutions ( well there really are more but that’s all we’re going to talk about)Saturated Remember, solubility and therefore saturation isb. Unsaturated dependent on temperature of solvent!!**On solubility chart, saturation is marked anywhere on the graphLine. Unsaturation is the area under the graph line.**
15 Concentration: the amount of solute dissolved in a GIVEN amount of solvent.Dilute – a little bit of solute in a specific amount of solvent.Concentrated – a lot of solute in the SAME amount ofsolvent.
16 Special solutions Suspensions Colloids Made of solute/solvent HeterogeneousSolute is suspended in the solvent for a period of timeSolute will eventually settle out of solutionOil and vinegarChocolate milkSand and waterA special kind of suspension where the solute is held in the solvent for an extended time period.HomogeneousThe use of an emulsifier is needed to keep the solute in suspension.MayonnaiseWhipped cream
17 Acid base comparison base acid Any aqueous solution that releases Hydrogen ions in solution.Generally, any compound that contains HydrogenWill react with metals to release Hydrogen gas.Has a pH between 1 and 6.9Tastes sourTurns blue litmus redWill react with a base to produce a salt + waterAny aqueous solution that releases hydroxyl ions (OH) in solution.Generally, any compound that contains the OH ion.Has a pH between 7 and 14Tastes bitterFeels slipperyTurns pink litmus blue.Will react with an acid to product a salt + water.
18 Acid: hydrochloric acid – HCl stomach acid sulfuric acid H2SO4 car battery acidnitric acid HNO fertilizerscarbonic acid H2CO3 acid found in sodasBases: sodium hydroxide – NaOH Dranohuman bloodpotassium hydroxide – KOH soapscalcium hydroxide – Ca(OH)2 hair relaxer, remover,Ca supplement in baby food.Neutralization reaction:Acid + base = salt + waterHCl NaOH NaCl HOHpH pH pH pH 7