Ch. 17 Water and Aqueous Systems Water is a ___________ molecule and therefore __________. Water forms _______________ ________ which strongly bonds the molecules together with each other. These intermolecular bonds give water some very unique properties: 1) High surface tension: acts like a thin “________” on the surface. _______________ are used to reduce water’s surface tension so it can “wet down” a surface such as clothing. bent polar hydrogen bonds skin Detergents “Water Strider”

Surface Tension of Water metal paper clip on water water forms “beads”

More Unique Properties of Water 2) Water forms 6-sided (hexagonal) ___________ of ice or snow and _____________ when it freezes. This makes ice ______ dense than water, so it ___________. crystals expands less floats 3) Water readily dissolves other _____________ substances and ionic solids/salts. polar

Aqueous Solutions There are two parts to a solution: 1) ____________- the dissolving medium which is typically a liquid or the substance in greater amount when 2 similar phases are mixed 2) _____________ - the substance that dissolves Solvent Solute

Examples of common solutions: Kool-aid = _________ in _______ Air = ____ in ____ sugar water O2 N2 14K gold = _______ in _________ silver gold

Examples of common solutions: __________ = copper in zinc Cola Drinks = sugar in water and ______ in ___________ Brass CO2 water

“Like Dissolves Like” This phrase means that polar solvents dissolve __________ solutes and nonpolar solvents dissolve ___________ solutes. Example: Mix together water, oil, table salt, and iodine (I2). What dissolves in what? ________________ ____________________________________ polar nonpolar The nonpolar oil will dissolve the nonpolar I2 and the water dissolves the salt since they are both polar.

nonpolar grease remover “Like Dissolves Like” nonpolar grease remover

“Unlike Polarity Cannot Dissolve Unlike” Vinegar & oil dressing will separate. Shake well before using!

Solutions & Electricity __________________- a solution that conducts electricity. __________________- a solution that does not conduct electricity. What Determines if a Solution will Conduct Electricity? A solution will conduct if there are ____________ ______________ (or _________), in the solution. Will a Solution be a Strong or Weak Electrolyte? Using the Solubility Chart: ______ = many ions in the solution = __________________ ______= few ions in the solution = ____________________ ______= no ions in the solution = _____________________ Electrolyte Nonelectrolyte charged particles ions S Strong Electrolyte sS Weak Electrolyte I Nonelectrolyte The Solubility Chart only lists ionic substances so if it isn’t in the chart it isn’t ionic and it isn’t an electrolyte!

The Light Bulb Demonstration bright glow weak glow no glow Strong Electrolyte Weak Electrolyte Nonelectrolyte completely dissociate into ions Examples: salt water, _______, drain cleaner incompletely dissociate into ions Examples: tap water, __________ no dissociation Examples: sugar in water, _____, alcohol oil HCl vinegar

air, brass, sugar water, salt water Types of Mixtures Type of Mixture Suspension Colloid True Solution Relative Particle Size Do the particles sink to the bottom over time? Can you filter out the particles? Do the particles scatter a beam of light? Examples Large Medium Small YES NO NO YES NO NO YES YES NO jello, paint, milk air, brass, sugar water, salt water muddy water Tyndall Effect

vinegar and oil salad dressing Suspensions vinegar and oil salad dressing

Colloidal Gold and Colloidal Silver Particle size ranges from 1 nm to 1000 nm. Colloidal Silver

True Solutions

Water Vocabulary hydrate- crystals that contain __________. (See Fig. 17.15 & Table 17.4) Example: CuSO4·5H2O copper (II) sulfate pentahydrate anhydrous- no _________ at all in the _______________. Examples: ___________ ______________, CaCl2 beads. water water crystal Anhydrous ammonia

Anhydrous Examples

Ch. 18-- Solutions Solution Vocabulary Solubility tells us how much _________ can dissolve in a certain amount of _____________ at a particular temperature and pressure to make a “__________________” solution. Solution Vocabulary _________________ solutions: the solution cannot hold any more solute. (Some solute may be sitting on the bottom of the container.) ________________ solutions: the solution could dissolve more solute ____________________ solutions: the solution is holding more than it should at the given temperature, and if you messed with the solution by shaking it or throwing in one more crystal, the whole thing would _________________ rapidly! solute solvent saturated Saturated Unsaturated Supersaturated crystallize

Supersaturated Sodium Acetate Solution

Factors that Affect Solubility 1) Temperature: a) Gas dissolved in Liquid: As temperature_____ , solubility ______. Examples: O2 in a fish tank…(________ water suffocates fish.) CO2 in soda… (_________ soda loses fizz.) inc. dec. Warm Warm

Factors that Affect Solubility: Temperature b) Solid dissolved in Liquid: As temperature ______ , solubility “generally” ________________. Example: sugar in hot tea vs. sugar in iced tea inc. increases

Factors that Affect Solubility: Temperature (abnormal behavior)

Factors that Affect Solubility 2) Pressure: a) Gas dissolved in Liquid: As pressure _____ , solubility ______. Examples: CO2 in soda: (made under _______ pressure) inc. inc. high

Factors that Affect Solubility: Pressure b) Solid dissolved in Liquid: As pressure ___________ , solubility ______ ______ _____________!! Since you cannot compress either a solid or a liquid, pressure has ____ effect on the solubility! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - inc. does not change no

Measuring the Concentration of a Solution ___________________: how much solute is dissolved in a certain amount of solvent at some given temperature and pressure. Qualitative Vocabulary _______________ : contains a small amount of solute _______________ : contains a large amount of solute Concentration Dilute Concentrated concentrated dilute

concentrated dilute

Quantitative Vocabulary: ____________: moles of solute per liter of solution _______________ ( ) = moles of solute ÷ Liters of solution Practice Problem: What is the molar concentration of an aqueous NaCl solution when 25.0 grams are dissolved in water to make 500 mL of solution? Molarity Molarity M moles Grams of solute = (M) x (L) x (Molar Mass) Molarity X Liters 25.0 g = (M) x (0.500 L) x (58.5 g/mole) Molarity = 0.855 M

Freezing Points and Boiling Points of Solutions Any solute added to a liquid will _____________ the freezing point of the liquid. In other words, if you put salt into water, instead of it freezing a 0˚C, it will freeze somewhere _________ zero depending on how concentrated the solution is. Uses include making homemade ice cream and melting ice on a sidewalk. lower below

Freezing Point Depression

Freezing Points and Boiling Points of Solutions Any solute added to a liquid will _____________ the boiling point of the liquid. In other words, if you put salt into water, instead of it boiling a 100˚C, it will boil somewhere ________ 100˚C depending on how concentrated the solution is. The solute decreases the solution’s vapor pressure. (See Fig. 18.15) Since ionic solids break up into multiple ions when dissolving, they actually change the F.P. & B.P. __________ than a molecule would. That’s one reason why we use salts to melt ice instead of using sugar! raise above more lowest freezing point & highest boiling point

Boiling Point Elevation Boiling Point (sea level): 219° F at 40 percent concentration 222° F at 50 percent 225° F at 60 percent

Ch. 20 Notes -- Acids and Bases What makes something an acid? Acid Properties: (1) tastes _______-- _______________ (2) corrosive to _________ (3) contains [ ___ ] (or [ _____ ] = “_______________” ions) (4) proton ([ ___ ]) __________-- Brønsted-Lowry Theory Example: HCl + H2O  ______ + ______ sour lemons metals H+ H3O+ hydronium H+ donor H3O+ Cl−

Examples of Common Acids: Pepsi, _________ juices, ___________, stomach acid, battery acid, _____________, ______ citrus aspirin vinegar DNA

Acid Vocabulary strong acid - readily ___________ to produce ______ [H+] ions in water Examples: _________, HNO3, _______ weak acid - produces a __________ amount of [H+] ions when in water Examples: HC2H3O2 (vinegar) , _________, _________ dissociate many H2SO4 HCl small H2CO3 lemon juice

Strong Acids vs. Weak Acids

Indicator Colors For Acids Indicators An indicator is a chemical that will change ___________ when placed in an acidic, basic or neutral environment. Indicator Colors For Acids litmus paper = _______ phenolphthalein = ___________ methyl orange = _______ colors red clear red

pH Paper : Indicator Colors Neutral Acidic Basic

Properties of Bases What make something a base? Base Properties: (…the opposite of acid properties) (1) tastes ________ -- ___________ peel , parsley, dark chocolate (2) feels _____________ -- ________ (3) contains [ _____ ] ions (4) proton ([H+]) ______________-- Brønsted-Lowry Theory Example: NH3 + H2O  ______ + _______ bitter banana slippery soap OH− acceptor NH4+ OH−

Indicator Colors for Bases litmus paper = _______ methyl orange = ____________ phenolphthalein = ______ blue yellow pink phenolphthalein Acid Base

Common Bases Examples of Common Bases: milk of magnesia, ___________, drain cleaner, soap, blood, ____________ tablets, ___________ ________. ammonia antacid baking soda

Strong Bases vs. Weak Bases strong base- readily __________ to produce ______ [OH−] ions in water Examples: NaOH , ________ weak base- produces a __________ amount of [OH−] ions when in water Examples: _____ (ammonia); Mg(OH)2 (milk of magnesia) dissociate many KOH small NH3

Conjugate Acid-Base Pairs Conjugate Acid- substance formed when a _______ gains a [H+] ion. Conjugate Base- substance formed when an ______ loses a [H+] ion. Practice Problems: Label the acid & base on the left side of the reaction and the conjugate acid & conjugate base on the right side. a) HCl + H2O  H3O+ + Cl− ______ ______ ______ ______ b) NH3 + H2O  NH4+ + OH− _____ ______ ______ ______ base acid acid base C.A. C.B. base acid C.A. C.B.

Measuring the Amount of H+ Ions in a Solution pH concentration _____ Scale- measures the _____________ of [H+] ions in a solution Formulas pH = − (log [H+]) [H+] = 10−pH With the pH scale, we have another way to define acids and bases: Acids have a pH _________7.0 Bases have a pH _________7.0 Neutral pH ___7.0 below above =

Practice Problems: 1) a) Calculate the pH of a 0.001 M HCl solution. 2) a) Calculate the pH of a 1 x 10- 5 M HCl solution. 3) What is the [H+] of a solution with a pH of 8.0? [H+] = 0.001 M So…pH = − (log 0.001 M) pH = 3 [H+] = 1 x 10–5 M So…pH = − (log 1 x 10–5 ) pH = 5 [H+] = 10−pH [H+] = 10−8 Molar or 1.0 x 10−8 M

Ch. 21 Notes -- Neutralization Neutralization Reactions When an acid and base are mixed, the reaction produces _______ and ___________. If the initial concentrations and volumes of the reactants are equal, the products will be ____________... (pH= 7.0) These reactions are _________ ___________ reactions! salt water neutral double replacement

Titration Mixing an acid with a base to determine a __________________ is called “titration.” An ____________ is used to determine when neutralization has occurred. ________________ Solution - the solution of known concentration The ______________ point is where the moles of [H+] ions equals the moles of [OH−] ions. concentration indicator Standard equivalence

Determining the Concentration of an Acid (or Base) by Titration (Macid)x(Vacid) = (Mbase)x(Vbase) Practice Problems: A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO3 solution? (2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of a 0.76 M HCl standard solution? ( ) x ( ) = ( ) x ( ) Macid 25 mL 1.0 M 18 mL Macid = 0.72 Molar ( ) x ( ) = ( ) x ( ) 0.76 M 55 mL 2.0 M Vbase Vbase = 20.9 mL