Solutions 1 Electrolytes and Nonelectrolytes Copyright © 2009 by Pearson Education, Inc.

solutionscolloidssuspensions < 1 nm> 100 nm -single atoms -small molecules -ions -polyatomic ions -aggregates of atoms, molecules or ions -macromolecules (proteins) -clumps of particles, -mineral grains such as sand Comparison of Solutions, Colloids, and Suspensions

solutionscolloidssuspensions < 1 nm> 100 nm More Comparison… transparent with Tyndall effect translucent (cloudy) molecular motion Brownian motion- colloidal particles moved by solvent movement by gravity coagulation – can settle never settle transparent (clear)

solutionscolloidssuspensions < 1 nm> 100 nm Light passage… Passage of lightScattering in beam Scattering in all directions Absorption of light

solutionscolloidssuspensions < 1 nm> 100 nm -dissolved in water electrolytes (salts) gases glucose -plasma proteins albumins globulins fibrinogen -cellular stuff red blood cells white blood cells platelets Using whole blood as an example…

tatang Miscible and Immiscible Liquids

tatang Pressure Changes with Solution Process

ELECTROLYTES NONELECTROLYTES Definition and properties: A substance that dissolves in water and conducts an electric current. (Has mobile ions) Definition and properties: A substance that dissolves in water and does not produce an electric current. (No mobile ions)

Electrolytes Nonelectrolytes  Examples: Acids, bases and salts  A. Strong Electrolyte: Dissociates completely into ions.  Strong acids: large ka (table K—HCl, HNO3,H2SO4,HBr &HI)  Strong Bases: large Kb (table F—soluble hydroxides)  Soluble salts: large ksp (table F-soluble salts)  B. Weak Electrolyte:  Doesn’t dissociate completely into ions  Weak acids: small ka (all the rest)  Weak bases: small kb (table F- insoluble hydroxides)  Insoluble salts: small ksp (table F- insoluble salts)  Alcohols (CxHyOH, suffic – ol)  Glycerin  Sugars (CxHyOz)  Note:  Dissociate: ionic substances dissociate (break down) into ions.  Ionize: Molecular substances need water to produce ions.

Classify the following as nonelectrolytes, strong electrolytes or weak electrolytes: HCl water NaCl (s) NaCl (aq) Vinegar NaOH (s) NaOH (aq) Sugar (s) Sugar (aq) Calcium carbonate (s) Calcium carbonate (aq) Ethanol Magnesium hydroxide(s) Magnesium hydroxide (aq)

Nonelectrolytes Water Sodium hydroxide (s) Sodium chloride (s) Sugar (s) Sugar (aq) Calcium carbonate (s) Ethanol Magnesium hydroxide (s) Strong Electrolytes HCl Sodium hydroxide (aq) Sodium chloride (aq) Weak Electrolytes Vinegar Calcium carbonate (aq) Magnesium hydroxide (aq)

Solutions: homogeneous mixtures Absence of settling Two components (at the least)-  Solute – the substance being dissolved  Solvent – the dissolving medium  usually water – aqueous solution can have multi-solute solutions - seawater

Types of solutes Na + Cl - Strong Electrolyte - 100% dissociation, all ions in solution high conductivity

Types of solutes CH 3 COOH CH 3 COO - H+H+ Weak Electrolyte - partial dissociation, molecules and ions in solution slight conductivity

Types of solutes sugar Non-electrolyte - No dissociation, all molecules in solution no conductivity

Solubility of Solutes in Water Temperature Solubility, g/100 mL water Most solids (endothermic hydration) Some solids (exothermic hydration) All gases

Dissolving process in water Na + Cl - 1. Overcome attractive forces in solid 2. Hydration of solute Orientation of water molecules around solute Click hereClick here for Chime structure

Types of attractive forces Na + Cl - For water: dipole-dipole For NaCl (s): ion-ion For hydrated ion: ion-dipole

How do I get sugar to dissolve faster in my iced tea? Stir, and stir, and stir Add sugar to warm tea then add ice Grind the sugar to a powder Fresh solvent contact and interaction with solute Greater surface area, more solute-solvent interaction Faster rate of dissolution at higher temperature

Units of Concentrations amount of solute per amount of solvent or solution Percent (by mass) = g solute g solution x 100 g solute g solute + g solvent x 100 = Molarity (M) = moles of solute volume in liters of solution moles = M x V L

Examples What is the percent of KCl if 15 g KCl are placed in 75 g water? %KCl = 15g x 100/(15 g + 75 g) = 17% What is the molarity of the KCl if 90 mL of solution are formed? mole KCl = 15 g x (1 mole/74.5 g) = 0.20 mole molarity = 0.20 mole/0.090L = 2.2 M KCl

How many Tums tablets, each 500 mg CaCO 3, would it take to neutralize a quart of vinegar, 0.83 M acetic acid (CH 3 COOH)? 2CH 3 COOH(aq) + CaCO 3 (s)  Ca(CH 3 COO) 2 (aq) + H 2 O + CO 2 (g) moles acetic acid = 0.83 moles/L x 0.95 L = 0.79 moles AA mole CaCO 3 = 0.79 moles AA x (1 mole CaCO 3 /2 moles AA) = 0.39 moles CaCO 3 mass CaCO 3 = 0.39 moles x 100 g/mole = 39 g CaCO 3 number of tablets = 39 g x (1 tablet/0.500g) = 79 tablets a quart the mole ratio molar mass

Solutes and Ionic Charge 23 In water, strong electrolytes produce ions and conduct an electric current. weak electrolytes produce a few ions. nonelectrolytes do not produce ions. Copyright © 2009 by Pearson Education, Inc.

Strong Electrolytes 24 Strong electrolytes dissociate in water, producing positive and negative ions. conduct an electric current in water. in equations show the formation of ions in aqueous(aq) solutions. H 2 O 100% ions NaCl(s) Na + (aq) + Cl − (aq) H 2 O CaBr 2 (s) Ca 2+ (aq) + 2Br − (aq)

Learning Check 25 Complete each for strong electrolytes in water. H 2 O A. CaCl 2 (s) 1) CaCl 2 (s) 2) Ca 2+ (aq) + Cl 2 − (aq) 3) Ca 2+ (aq) + 2Cl − (aq) H 2 O B. K 3 PO 4 (s) 1) 3K + (aq) + PO 4 3− (aq) 2) K 3 PO 4 (s) 3) K 3 + (aq) + P 3− (aq) + O 4 − (aq)

Solution 26 Complete each for strong electrolytes in water: H 2 O A. CaCl 2 (s) 3) Ca 2+ (aq) + 2Cl − (aq) H 2 O B. K 3 PO 4 (s) 1) 3K + (aq) + PO 4 3− (aq)

Weak Electrolytes 27 A weak electrolyte dissociates only slightly in water. in water forms a solution of a few ions and mostly undissociated molecules. HF(g) + H 2 O(l) H 3 O + (aq) + F - (aq) NH 3 (g) + H 2 O(l) NH 4 + (aq) + OH - (aq)

Nonelectrolytes dissolve as molecules in water. do not produce ions in water. do not conduct an electric current. 28 Copyright © 2009 by Pearson Education, Inc.

Equivalents 29 An equivalent (Eq) is the amount of an electrolyte or an ion that provides 1 mole of electrical charge (+ or -). 1 mole of Na + = 1 equivalent 1 mole of Cl − = 1 equivalent 1 mole of Ca 2+ = 2 equivalents 1 mole of Fe 3+ = 3 equivalents

Electrolytes in Body Fluids 30 In replacement solutions for body fluids, the electrolytes are given in milliequivalents per liter (mEq/L). Ringer’s Solution Na mEq/LCl − 155 mEq/L K + 4 mEq/L Ca 2+ 4 mEq/L The milliequivalents per liter of cations must equal the milliequivalents per liter of anions.

Electrolytes in Body Fluids 31 Copyright © 2009 by Pearson Education, Inc.

Learning Check 32 A. In 1 mole of Fe 3+, there are 1) 1 Eq.2) 2 Eq. 3) 3 Eq. B. In 2.5 moles of SO 4 2−, there are 1) 2.5 Eq.2) 5.0 Eq. 3) 1.0 Eq. C.An IV bottle contains NaCl. If the Na + is 34 mEq/L, the Cl − is 1) 34 mEq/L.2) 0 mEq/L. 3) 68 mEq/L.

Solution 33 A. 3) 3 Eq. B. 2) 5.0 Eq. 2.5 mole SO 4 2− x 2 Eq = 5.0 Eq 1 mole SO 4 2− C. 1) 34 mEq/L

Colligative Properties Explain how solutes effect the properties of a solution. Use Raoult’s Law to calculate vapor pressure of solution. Explain Fractional Distillation & its uses. Explain how solutes effect boiling & freezing points.

Colligative Properties Properties determined by the number of particles in solution rather than the type of particles. Vapor Pressure Freezing Point Boiling Point Rate of Diffusion

How Vapor Pressure Depression Occurs Solute particles take up space in a solution. Solute particles on surface decrease # of solvent particles on the surface. Less solvent particles can evaporate which lowers the vapor pressure of a liquid.

Vapor Pressures of Pure Water and a Water Solution The vapor pressure of water over pure water is greater than the vapor pressure of water over an aqueous solution containing a nonvolatile solute. Solute particles take up surface area and lower the vapor pressure

Raoult’s Law Vapor pressure of a solution varies directly as the mole fraction of solvent Vapor Pressure Solution = (mole fraction solvent )(Vapor Pressure solvent )

Raoult’s Law (continued) A solution of water and glucose with a mole fraction of 0.5 will have a vapor pressure that is 0.5 times the vapor pressure of water alone.

Ideal Solution All intermolecular attractions are the same. Solute-Solute Solvent-Solvent Solute-Solvent Attractions are the same

Raoult’s Law: Depression of Vapour pressure VP of solution relates to VP of pure solvent P A = X A P * A Solutions that obey Raoult’s law are called ideal solutions.

Raoult’s Law Example The total vapour pressure and partial vapour pressures of an ideal binary mixture Dependence of the vp on mole fractions of the components.

An Ideal Solution Benzene and toluene behave almost ideally Follow Raoult’s Law over the entire composition range.

Henry’s Law Henry’s law relates the vapour pressure of the solute above an ideally dilute solution to composition.

The Ideal Dilute Solution Ideal Dilute Solution  Solvent obeys Raoult’s Law  Solute obeys Henry’s Law