Special Double Replacement Reactions Acid-Base Chemistry Special Double Replacement Reactions

15.2 & 15.3The Nature of Homogeneous and Heterogeneous Systems Homogeneous Systems – Solutions Aqueous- water containing dissolved substance(s) (note: not all solutions are aqueous) Solvent- “does the dissolving” Solute- “is dissolved” Heterogeneous Systems – Colloids and Suspensions Contains a dispersed phase in a dispersion medium Particles in colloids and suspensions are larger than solute particles

Solutions, Colloids and Suspensions Property Solution Colloid Suspension Particle Size 0.1-1nm 1-1000nm 1000nm or larger Particles Settle? No Yes Tyndall Effect? Type of Mixture Homogeneous Heterogeneous

Characteristics of Heterogeneous Mixtures The Tyndall Effect Scattering of visible light by particles Brownian Motion Particles exhibiting the Tyndall Effect move erratically. This movement is caused by the collision of the dispersed particles with the molecules in the media.

Characteristics of Heterogeneous Mixtures Coagulation Colloidal particles adsorb charged particles from the surrounding media. Repulsion between like charged particles keeps particles from settling. Emulsions Colloidal dispersion of a liquid in a liquid. Know examples from table 15.3 on page 460

What is Dissolving? Term for solute particles being surrounded by solvent molecules = Solvation

Properties of Solutions 16.1 and 16.2 Solubility Concentration

Factors Influencing Dissolving Rate of dissolving- influenced by: Agitation, temperature, particle size (surface area) Amount that can be dissolved- influenced by: Temperature/Pressure

Solubility Curves Solubility- the maximum amount of solute per a given amount of solvent (usually 100g water)

Types of Solutions Supersaturated Solution of NaNO3 Unsaturated Solution of NaNO3

Interpreting Solubility Curves Solids in water- generally more soluble at higher temperatures (note: Na2SO4) Gases in water- solubility decreases with increased temperature

Concentrated vs. Dilute Concentrated Sugar Solution Dilute Sugar Solution

Solution Concentration Molarity= moles of solute per Liters of solution (M=n/V) Example: Calcuate the molarity when 75.0 grams of MgCl2 is dissolved in 500.0 mL of solution.

Practice Determine the molarity of the following solutions: 120. grams of calcium nitrite in 240.0 mL of solution. 3.79 M 98.0 grams of sodium hydroxide in 2.2 liters of solution. 1.1 M How many grams of solid are required to make 0.75 L of 0.25 M Na2SO4 Dissolve 27 g Na2SO4, dilute to 0.75 L

Dilution of Solutions: M1V1= M2V2 (note: moles of solute remain constant) Example: How many mL of a 5.0M stock solution would you need to prepare 100.0mL of 0.25M H2SO4? 5.0 mL

Practice If I have 340 mL of a 0.50 M NaBr solution, what will the concentration be if I add 560 mL more water to it? 0.19 M To what volume would I need to add water to the solution in the previous problem to get a solution with a concentration of 0.0250 M? 6800mL

Percent Solution Percent by Mass %mass= (mass of solute/mass of solution)*100 What is the percent by mass of NaHCO3 in a solution of 20g NaHCO3 in 600 g of solution? Percent by Volume (both solute and solvent are liquids) %volume = (volume of solute/volume of solution)* 100 If you have 100.0 mL of a 30.0% ethanol solution, what volumes of ethanol and water are in the solution?

Acids and Bases 19.1-19.4

Acids and Bases Acids Bases Taste Sour Bitter Feel Irritating (burning) Slippery React with metals Produce H2 gas NR Change indicator Colors? Yes Characteristic Formula H in front or COOH at end OH at the end

Types of Acids Oxyacids (H2SO4) - ic acids from ate ions Mono-, di-, and triprotic acids- have 1, 2, or 3 H atoms that can become ionized (note: not all compounds that contain H are acidic and not all hydrogens in an acid will necessarily ionize) Recall Naming Rules for: Binary Acids (HCl) Hydro _______ ic Acid Oxyacids (H2SO4) - ic acids from ate ions - ous acids from ite ions

Arrhenius Definition of Acids Acids- generate H+ ions in water Bases-generate OH- ions in water  

Measuring pH pH = -log[H+] Acidic Solutions pH <7, [H+] >1x 10-7 Neutral Solutions pH =7, [H+] =1x 10-7 Basic Solutions pH >7, [H+] <1x 10-7

Strong vs. Weak Strong Bases Strong acids Group I or IIA with OH HCl Determined by the extent of ionization Strong Bases Group I or IIA with OH Strong acids HCl HBr HI HClO4 HNO3 H2SO4 Small dissociation constants (Ka or Kb) = weak acids and bases Large dissociation constants = strong acids and bases

Neutralization Reactions- Acid and base react to yield water and a salt

Titration- Slowly adding a solution of known concentration to one of unknown concentration until a neutral solution is formed.

Acid-Base Indicators Used to predict endpoint of titration An acid or base that undergoes dissociation in a known pH range An indicators acid and base form have different colors