Ch. 15 Solutions 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: 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. “Water Strider” bent polar hydrogen bonds skin Detergents

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

Water makes 6-sided (hexagonal) ___________ of ice or snow. More Unique Properties of Water Water readily dissolves other _____________ substances and ionic solids/salts. crystals polar

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 Aqueous Solutions Solvent Solute

Examples of common solutions: Kool-aid = _________ in _______ Air = ____ in ____ 14K gold = _______ in _________ sugarwater O2O2 N2N2 silvergold

Examples of common solutions: __________ = copper in zinc Cola Drinks = sugar in water and ______ in ___________ Brass CO 2 water

This phrase means that polar solvents dissolve __________ solutes and nonpolar solvents dissolve ___________ solutes. Example: Mix together water, oil, table salt, and iodine (I 2 ). What dissolves in what? ________________ ____________________________________ “Like Dissolves Like” polar nonpolar The nonpolar oil will dissolve the nonpolar I 2 and the water dissolves the salt since they are both polar.

“Like Dissolves Like” nonpolar grease remover

“Like Dissolves Like” Vinegar & oil dressing will separate. Shake well before using!

Solution Vocabulary _______________ : two liquids that can dissolve in each other Example: ____________ in water _________________ : the liquids don’t mix Example: _____ and water Miscible Immiscible alcohol Oil

Factors that Affect Solubility Tested Dissolved Oxygen, Conductivity, Salinity (salt concentration), and Temperature.

Factors that Affect Solubility Tested Dissolved Oxygen, Conductivity, Salinity (salt concentration), and Temperature.

Factors that Affect Solubility Tested Dissolved Oxygen, Conductivity, Salinity (salt concentration), and Temperature.

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 concentrateddilute Concentration Dilute Concentrated

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 M 25.0 g x ________________ = Molarity = M M = ___________________ 1 mol 58.5 grams mol L

Making a Solution of a Required Concentration # of moles ÷ # of liters = Molarity

Making Dilutions Dilution: Making a solution _______ concentrated by ________ more ___________. Important: When diluting acids: “Add acid to water, do as you ought-er.” M 1 xV 1 =M 2 xV 2 M 1 -- the initial concentration of the solution. V 1 -- the initial volume of the original solution that is going to be diluted with water. M 2 -- the final concentration of the solution after it’s diluted with water. V 2 -- the total volume of the final solution after it has been diluted with water. lessadding solvent

Making Dilutions M 1 xV 1 =M 2 xV 2 Practice Problems: 1) The science department buys HCl in large bottles that have a concentration of 12 Molar. The science teacher then dilutes the acid for labs. How would the teacher make 2.0 liters of a 2.5 M HCl solution from this “stock” solution? 2) What is the final concentration of a sugar solution if 300 mL of water is added to 500 mL of a 2.5 M sugar solution? ( ) ( ) = ( ) ( ) V 1 = L ( ) ( ) = ( ) ( ) M 2 = 1.56 M 12 MV1V1 2.5 M2.0 L Take L of the stock solution and add it to some water and then add enough water to make a final volume of 2.0 liters. 2.5 M500 mL800 mLM2M2

Calibration Curves A standard solution is a solution of__________________. These solutions can be used to predict properties of an unknown solution. At least _________ data points are used and then plotted with a line of best fit. known concentration three Beer’s Law

Calibration Curves If spectrometer reads the absorbance at 0.48 what is the molarity? What would you predict the absorbance of a 7M solution to be? 3.12 M 0.62

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 + H 2 O  ______ + ______ sourlemons metals H+H+ H3O+H3O+ hydronium H+H+ donor Cl − H3O+H3O+

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: NH 3 + H 2 O  ______ + _______ bitterbanana slipperysoap OH − acceptor NH 4 + OH −

Examples of Common Acids: Pepsi, _________ juices, ___________, stomach acid, battery acid, _____________, ______ citrusaspirin vinegarDNA Common Bases

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

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 = ___________ red cabbage juice (universal indicator) = ________ methyl orange = _______ colors red clear red

Indicator Colors for Bases litmus paper = _______ methyl orange = ____________ red cabbage juice (universal indicator) =________ phenolphthalein = ______ AcidBase phenolphthalein blue yellow blue pink

Universal pH Paper : Indicator Colors Acidic Basic Neutral

Acid Vocabulary strong acid - readily ___________ to produce ______ [H + ] ions in water Examples: _________, HNO 3, _______ weak acid - produces a __________ amount of [H + ] ions when in water Examples: HC 2 H 3 O 2 (vinegar), _________, _________ dissociatesmany HCl H 2 SO 4 small H 2 CO 3 lemon juice

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) Other Vocabulary _______________- another term for basic solutions _______________- a substance that can act as both an acid and a base Examples: ___________, ____________ dissociatemany KOH small NH 3 Alkaline Amphoteric H2OH2OHCO 3 − Base Vocabulary

Measuring the Amount of H + and OH − Ions in a Solution _____ Scale- measures the _____________ of [H + ] ions in a solution _____ Scale- measures the concentration of [ ____ ] ions in a solution Formulas pH = − (log [H + ]) pOH = −(log [OH − ]) [H + ] = 10 −pH [OH − ] = 10 −pOH [H + ] x [OH − ] = 1 x 10 −14 pH + pOH = 14 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 pHconcentration pOHOH − below above =

pH Testing

Alkalinity Testing

Practice Problems: 1)Calculate the pH of a M HCl solution 2) What is the pH of a 4 x M KOH solution? 3)What is the concentration of [H + ] ions in a NaOH solution with a pH of 8.50? 4) What is the concentration of [H + ] ions in a HNO 3 solution with a pH of 1.50 [H + ] = MSo…pH = − (log M)pH = 3 [H + ] = 10 −pH [H + ] = 10 −8.5 Molar or 3.16 x 10 −9 M [H + ] = 4 x MSo…pH = − (log 4 x M)pH = 8.3 [H + ] = 10 −pH [H + ] = 10 −1.5 Molar or M

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) All neutralization reactions are ___________ replacement reactions. HX + M(OH)  ______ + ______ salt water neutral double MX H2OH2O (“Salt”)

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 of neutralization when titrating At the ______ point, the moles of [H + ] ions = moles of [OH − ] ions. concentration indicator Standard End Point end

(M acid )x(V acid ) = (M base )x(V base ) Practice Problems: (1)A 25 mL solution of HNO 3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO 3 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? Determining the Concentration of an Acid (or Base) by Titration ( ) x ( ) = ( ) x ( ) M acid 25 mL1.0 M18 mL M acid = 0.72 Molar 0.76 M55 mL2.0 MV base V base = 20.9 mL