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

Suspensions and Colloids 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 Tyndall Effect: The scattering of light by suspended particles Emulsion: Colloidal suspension of a liquid in a liquid. (Mayo, margarine, butter, milk) 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

Strong v. 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

pH pH = -log[H+]

Strength of Acids – Dissociation constants