Solution Stoichiometry Lecture 1 Adapted From

Solutions Two things that make up a mixture –Solute = thing being dissolved –Solvent = thing doing the dissolving What affects dissolving? –Nature of solute –Solvent 1)Amount 2)Temperature 3)Type of solvent oWater = aqueous oAlcohol = tincture

Water ~ “universal solvent” Shape of molecule Polar covalent molecule –Polar = uneven distribution of charge Which side is partially negative? … positive? –Covalent = sharing of electrons Where are the electrons located in the bond?

Water ~ “universal solvent” Why is the unequal distribution of charge important?? –Strong water ion attraction –Hydration Attraction of ions to the uneven charges of water ions/nacl/solutionSalt.htmhttp://mutuslab.cs.uwindsor.ca/schurko/animat ions/nacl/solutionSalt.htm

Solubility Ability of solvent to dissolve the solute at a given temperature What happens to…. –Ionic compounds (metal + nonmetal)? Break up into ions (some more than others), allow electric current to flow –Covalent molecules (all nonmetals)? Dissolve as molecules, stay together –Nonpolar and polar? Don’t dissolve

HUGE POINT #1 Solubility vs. Ionization –Solubility Amount that dissolves –Ionization What happens when it dissolves

Strong Electrolytes Ionizes completely Conduct electricity

What are examples of strong electrolytes? 1.Soluble salts - completely hydrated into ions in water

HUGE POINT #2 Solubility Rules!!! –We’ll tackle one each day –Pg. 152 in the book

SOLUBILITY RULES 1.Most nitrate (NO 3 - ) salts are soluble. 2.Most salts containing the alkali metal ions (Group I) or the ammonium ion (NH 4 + ) are soluble. 3.Most chloride, bromide, and iodide salts are soluble. EXCEPTIONS: Ag +, Pb 2+, Hg 2 2+

SOLUBILITY RULES 4.Most sulfate salts are soluble. EXCEPTIONS: BaSO 4, PbSO 4, Hg 2 SO 4, and CaSO 4 5.Most hydroxide salts are only slightly soluble. SOLUBLE = NaOH and KOH MARGINALLY SOLUBLE = Ba(OH) 2, Sr(OH) 2, Ca(OH) 2 6.Most sulfide (S 2- ), carbonate (CO 3 2- ), chromate (CrO 4 2- ), and phosphate (PO 4 3- ) salts are only slightly soluble.

Demonstration - Visible Line How to write up demos Equation Why does this happen? What’s visible? CA4/STHTM/PBNO/PBNONAIX.HTMhttp://jchemed.chem.wisc.edu/JCESoft/cca/C CA4/STHTM/PBNO/PBNONAIX.HTM

What are examples of strong electrolytes? 2.Strong acids produce H + in water, completely ionize

STRONG ACIDS Who are the strong acids? oHCl = hydrochloric acid ______ _____ oHBr = hydrobromic acid______ _____ oHI = hydroiodic acid______ _____ oHNO 3 = nitric acid______ _____ oH 2 SO 4 = sulfuric acid (careful)______ _____ oHClO 3 = perchlorous acid______ _____ oHClO 4 = perchloric acid______ _____

What are examples of strong electrolytes? 3.Strong bases Group IA and IIA (Ca, Ba, Sr) with OH - Produce OH - in water, completely ionize May have low solubility, but all ionize No rule about one at a time

Weak electrolytes Do not ionize completely –Huge range Examples –Salts that don’t completely ionize –Any acid not listed as “strong” –Any base not listed as “strong” Demo

Nonelectrolytes Anything that doesn’t dissolve or doesn’t produce ions Examples 1.Insoluble salts (solubility rules!!) 2.Covalent compounds REMEMBER DIFFERENCE BETWEEN SOLUBILITY AND IONIZATION

Solution calculations Molarity –Measures the concentration –Molarity = moles / Liters (before mixing) –Examples

Solution calculations Dilution –The addition of water to change the concentration –Equation M 1 V 1 = M 2 V 2 –Examples

Solution calculations Concentration of ions –Examples