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Example of a heterogenous mixture
Example of a homogenous mixture

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Milk and Soil because they are not uniform
Saltwater solution

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Soluble

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Capable of being dissolved

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Solution

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A homogenous mixture of 2 or more substances in a single phase. Same throughout.

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Solvent

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The dissolving medium in a solution

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Solute

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The substance being dissolved

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The solute is generally designated as that component of a solution that is of lesser quantity.

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TRUE.

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The dissolved solute particles are so small that they cannot be seen.

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TRUE.

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Alloys can have higher strength and greater resistance to corrosion than the pure metals. alloys are solid solutions in which the atoms of 2 or more metals are uniformly mixed

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true dat doe

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some solute-solvent combinations for solutions
Solute>solvent>example

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Gas>Gas>Oxygen in Nitrogen
Gas>Liquid>Carbon dioxide in h20
liquid>gas>water in air
liquid>liquid>alcohol in water
liquid>solid> mercury in silver & tin (dental amalgam)
solid>liquid>sugar in water
solid>solid>copper in nickel (monel alloy)

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Suspension

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If the particles in a solvent are so large that they settle out unless the mixture is constantly stirred or agitated. ex. a jar of muddy water. can be seperated by filters cuz dey r heterogenous mixtures.

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Colloids

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Particles that are intermediate in size between those in solutions and suspensions form mixtures known as colloidal dispersions. 1nm-1000nm

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ex colloids

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After large soil particles settle out of muddy water, the water is often still cloudy because colloidal particles remain dispersed in the water.colloidal particles make up the dispersed phase, and water is the dispersing medium.

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class of colloid>phases>example
L=liquid
S= solid
G=gas

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Sol> S dispersed in L>paints, mud
Gel>S network extending thru L>gelatin
L emulsion>L dispersed in a L>milk, mayo
Foam>G dispersed in L>shaving/whipped cream
S Aerosol>S dispersed in G>smoke, airborne matter
L Aerosol>L dispersed in G>fog, moist, clouds
S Emulsion>L dispersed in S>cheese, butter

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Tyndall Effect

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Light is scattered by colloidal particles dispersed in a transparent medium. Can be used to distinguish between a solution and a colloid. headlight beam on a foggy night.

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Brownian motion by Robert Brown

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The individual particles of a colloid can be detected under a microscope if a bright lught is cast on the specimen at a right angle. The particles, which appear as tiny specks of ligh, are seem to move rapidly in a random motion.

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Solution properties

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Homogenous. Can be atoms, ions, and molecules. Do not separate on standing. Cannot be separated by filtration. Do not scatter light.

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Colloids

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Heterogenous. Dispersed; can be aggregates or large molecules. Do not separate on standing. Cannot be separated by filtration. Scatter light (tyndall effect)

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Suspension properties

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Heterogenous. Suspended; can be large particles or aggregates. Particles settle out. can be separated by filtration. May scatter light, but are not transparent.

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Electrolyte

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A substance that dissolves in water to give a solution that conducts electric current. ex. NaCl

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Substances that dissolve in water are classfied according to whether they yield molecules or ions in solution

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When an ionic compund dissolves, the positive and negative ions separate from each other and are surrounded by water molecules

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Does a solution containing neutral solute molecules conduct electric current?

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No because it does not contain mobile charged particles.

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Nonelectrolyte

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A substance that dissolves in water to give a solution that does not conduct an electric current. ex sugar

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electrodes

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conductors that are attached to a power supply and that make electric contract with the test solution

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For a current to pass thru the light bulb filament

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the test solution must provide a conducting path between the 2 electrodes

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A nonconducting solution

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is like an open switch between the electrodes, and there is no current in the circuit

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molecules or ions of the solute are attracted by the solvent. the dissolution process occurs at the surface of the solute, it can be speeded up if the surface area of the solute is increased

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crushing sugar that is in cubes or large crystals increases the surface area as well as the more finely divided a substance is, the greater the surface area per unit mass and the more quickly it dissolves. same as the effect of stirring.

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As the temperature of the solvent increases, solvent molecules move faster, and their average kinetic energy increases

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at higher temps, collisions between the solvent molecules and the solute are more frequent and are of higher energy then at lower temps. this helps separate solute molecules from 1another and to disperse them among the solvent molecules.

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for every combination of solvent with a solid solute at a given temperature, there is a limit to the amount of solute that can be dissolved.

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Sugar molecules leave the solid surface and move about at random in the solvent. some of these dissolved molecules may collide with the crystal and remain there (recrystallize)

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Solution equilibrium

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the physical state in which the opposing processed of dissolution and crystallization of a solute occur at equal rates.

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saturated solution

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A solution that contains the maximum amount of dissolved solute

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unsaturated solution

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a solution that contains less solute than a saturated solution under the existing conditions

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supersaturated solution

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contains more dissolved solute than a saturated solution contains under the same conditions. may remained unchanged for a long time. once crystals begin to form, the process continues until equilibrium is reestablished at the lower temps.

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Solubility

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The solubility of a substance is the amount of that substance required to form a saturated solution with a specific amount of solvent at a specified temperature. for gases, the pressure must be specified.

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The rate at which a solid dissolves is unrelated to solubilty.

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the maximum aMOUNT OF SOLUTE THAT DISSOLVES and reaches equilibrium is always the same under the same conditions.

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Like dissolves like

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useful rule for predicting whether one substance will dissolve in another. depends on the type of bonding, the polarity or nonpolarity of molecules and the intermolecular forces between the solute and solvent.

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Dissolving Ionic compounds in aqueous solution
-the polarity of water molecules plays an important role.
-The charged ends of water molecules attract the ions in the ionic compunds and surround them to keep them separated from the other ions in the solution. The attraction between water molecules and the ions is strong enough to draw the ions away from the crystal surface and into solution.

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As hydrated ions diffuse into the solution, other ions are exposed and are drawn away from the crystal surface by the solvent. The entire crystal gradually dissolves, and hydrated ions become uniformly distributed in the solution.

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Hydration

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Solution process with water as the solvent. ions are hydrated.

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when crystallized from aqueous solutions, some ionic substances form crystals that incorporate water molecules. these crystalline compounds, known as hydrates, retain specific ratios of water molecules.

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heating the crystals of a hydrate can drive off the water of hydration and leave the water of hydration returns to the solvent. the behavior of the anhydrous form. dissolving either form results in a system containing hydrated ions and water.

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ionic componds are genreally not soluble in nonpolar solvents such as CCl4. the nonpolar solvent molecules do not attract the ions of the crystal strongly enough to overcome the forces holding the crystal together.

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true

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immiscible

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liquid solutes and solvents that are not soluble in each other. ex toluene and water

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nonpolar substances like fats oils and greases are quite soluble in nonpolar liquids such as gasoline and toluene.

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the only attractions between the nonpolar molecules are weak London forces. the intermolecular forces exsiting in the solution are very similar to those in pure substances. thus, the molecules can mix freely with 1 another.

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miscible

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Liquids that dissolve freely in 1 another in any proportion. es benzene and carbon tetrachloride

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The intermolecular forces in the mixture are so similar to those in the pure liquids that the liquids are mutually soluble in all proportions.

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ethanol is intermediate in polarity between water and carbon tetrachloride. it is not as good a solvent for polar or ionic substances as water is. sodium chloride is only slightly soluble in ethanol. ethanol is a better solvent than water for less-polar substances because the molecule has a nonpolar region..

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increases in pressure increase gas solubilities in liquids.

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as the amount of dissolved gas increases, some molecules begin the escape and reenter the gas phase. an equilibirum is evetually established.

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INcreasing the pressure of the solute gas above the solutions puts stress on the equilibirum. MOlecules collide with the liquid surfaces more often. the increase in pressure is partially offset by an increase in the rate of gas molecules entering the solution. in turn, the increase in the amount of dissolved gas causes an increas in the rate at which molecules escape from the liquid surface and become vapor.

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entually, equilibirum is restored at the higher gas solubilty. as espected from Le Chatelier's principle, an increase in gas pressure causes equilibirum to shift so the fewer molecules are in the gas phase

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Henry's Law

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The solubility of a gas in a liquid is directly proportional to the partial presuure of that has on the surface of the liquid. applies to gas-liquid solutions at constant temp.

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effervescence

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The rapid escape of a gas from a liquid in which it is dissolved

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Increasing the temperature usually decreases gas solubilty. As the temp increases, the average kinetic energy of the molecules in solution increases. A greater number of solute molecules are able to escape from the attraction of solvent molecules and return to the gas phase.

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At higher temperatures, equilibrium is reached with fewer gas molecules in solution and gases are generally less soluble.

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Solvated

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A solute particle that is surrounded by solvent molecules.

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Heat of solution

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The net amount of heat energy absorbed or released when a specific amount of solute dissolves in a solvent. In the gaseous state, molecules are so far apart that there are virtually no intermolecular forces of attraction between them. solute-solute interaction has little effect on the heat of a solution of a gas.

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concentration

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the concentration of a solution is a measure of the amount of solute in a given amount of solvent or solution

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dilute

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there is a relatively small amount of solute in a solvent.

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concentrated

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there is a relatively large amount of solute in a solvent.

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molarity

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the number of moles of solute in one liter of solution.

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molality

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the concentration of a solution expressed in moles of solute per kilogram of solvent.

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the molar concentration of a solution represents the ratio of moles of solute to liters of solution

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the molal concentration of a solution represents the ration of moles of solute to kilogram of solvent.

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