Study Guide Exam 4 - Introductory Chemistry | CH 104, Study notes of Chemistry

Download Study Guide Exam 4 - Introductory Chemistry | CH 104 and more Study notes Chemistry in PDF only on Docsity! Exam 4 Outline CH 104 Fall 2009 You need to bring a pencil, a calculator and your ACT card. ALL other materials must be left at the front of the classroom in an unsecured area. ALL cell phones must be turned off during exam. Chapter 9: Solutions 1. Kinds of mixtures of liquids (Section 9.1)  Solution oVery small particles oCannot be filtered oTransparent  Colloid oMedium-sized particles oScatter light  Suspension oLarge particles oCan be filtered (will settle out if not stirred) oOpaque 2. Identify the solute and solvent in a solution  The “solute” is dissolved in the “solvent”  Presence of solute lowers freezing point and raises boiling point of solvent (Section 9.11) 3. Solubilty (Sections 9.4-9.6)  Like dissolves like oPolar compounds dissolve polar compounds oNonpolar compounds dissolve nonpolar compounds  Ionic compounds disassociate into ions oEach ion is solvated (surrounded) by water molecules oCations interact with the negative ends of dipolar bonds in water (oxygens) oAnions interact with the positive ends of the dipolar bonds in water (hydrogens) oThese solutions can conduct electricity (electrolytes)  Electrolytes and nonelectrolytes (Section 9.9) o Ionic compounds that completely disassociate in water conduct electricity well and are strong electrolytes o Ionic compounds that only partially disassociate in water conduct electricity poorly and are weak electrolytes oCovalent compounds that do not disassociate in water do not conduct electricity and are nonelectrolytes  Measuring solubility (Section 9.4) oSolubility describes the maximum amount of a material that will dissolve in a given amount of solvent under given conditions (temperature, pressure) oUnits of solubility are typically in g solute / g solvent oSaturated solutions have the maximum amount that will dissolve + a small amount of solid oUnsaturated solutions have less than the maximum amount oGenerally, the solubility of solids increase with increasing temperature while the solubility of gases decreases (Section 9.5 oGenerally, the solubility of gases increases with increasing pressures (Section 9.6)  Solubility rules (slide 8, Chapter 9 graphics) MEMORIZE THESE oSalts containing NH4 +, Li+, Na+, and K+ cations are always soluble oSalts containing NO3¯ and acetate (C2H3O2¯) anions are always soluble oSalts containing Cl¯, Br¯, and I¯ are soluble except with Ag+, Pb2+ and Hg2 2+ oSalts containing SO4 2¯ are soluble except with Ba2+, Pb2+,Ca2+,Sr2+ oSalts containing CO3 2¯, S2¯, PO4 3¯ and HO¯ are insoluble except with NH4 +, Li+, Na+, and K+ 4. Concentration (Section 9.7)  Molarity oMolarity (M) = moles solute / L of solution oCan be used as a conversion factor to find moles in a given volume or volume containing a given number of moles oDo not forget that moles are related to mass using the molar masses!  Percent mass/volume (m/v) concentration omass/volume % = (g solute / milliliters solvent) × 100% o this can be used as a conversion factor to find grams in a given volume or volume containing a given mass  Parts per million (ppm) o “parts” in a million of chosen units o (mass solute/ mass of solution) × 106  To calculate pH of a buffer: Ka = [H3O +][A-] [HA] Rearranging, [H3O +] = Ka [HA] [A-] Then, pH = –log[H3O +] 8. Neutralization reactions (Section 10.14)  Reaction of acid and base to give water and a salt  Can be performed with acid or base solution of known concentration to find concentration of the other solution (titration, Section 10.15)  Know how to calculate concentration from titration data (see Fig 10.9) Chapter 11: Nuclear Chemistry 1. Know definition of radioactive isotope 2. Identify the types of radiation as alpha particles, beta particles, positrons, or gamma radiation (Section 11.2)  Know symbols, mass number, and charge of each 3. Write an equation for an atom that undergoes radioactive decay (Section 11.4)  You must be able to balance nuclear reactions i. Balance mass numbers ii. Balance atomic numbers iii. Remember that when balancing reactions, beta particles and positrons act as if they have atomic numbers of -1 and +1, respectively 4. Calculate the amount of radioisotope that remains after a given number of half-lives (Section 11.5)  Know definition of half-life  Be able to calculate amount of radioisotope remaining after given number of half-lives have passed 5. Describe nuclear fission and fusion (Section 11.11)  Be able to define and identify each process o Fission: fragmenting of a heavy nucleus o Fusion: joining together two light nuclei  Know definition of chain reaction and critical mass