Chapter 13.1-13.4 problems November 28, 2011 • What IMF(s) is/are present when… a) KCl is dissolved in H2O b) carnauba wax dissolves in castor oil c) Methanol (CH3OH) vs CCl4 • Arrange the following in increasing solubility: A B C • Which solvent will yield the highest concentration of NaCl? a) b) • Which will have the highest concentration in diethyl ether ( )? A. HCl (g) B. NaCl (s) C. H2O Why will washing your face with soap make your face “dryer”? (clue: remember your lipbalm experiment) • When NH4Cl dissolves in water, the solution becomes colder… A) Is ΔHsol’n >, < or = to 0? B) Is ΔHlattice >, <, or = to ΔHhydration ? C) Is the dissolution mostly due to ΔH or ΔS of mixing? • CHARGE DENSITY affects ΔHhydration. Which one will have a higher (more negative) ΔHhydration ? A) Na+ , Rb+ B) Br-, IC) Ca2+, Na+ • Which best depicts the dissolution of NaI (exothermic)? • Which one best describes the enthalpy diagram of dissolving KBr in hexane? • Henry’s Law constant (kH) of O2 in water at 20oC is 1.28 x 10-3 mol/L-atm. a) How many grams will dissolve in 2.50 L H2O that is in contact with pure O2 at 1.00 atm? b) How many grams will dissolve in 2.50 L H2O that is in contact with pure O2 at 0.209 atm? • Express the concentration of concentrated HCl (12M)? Assume density of solution to be that of water: 1.00g/mL a) Molality b) %w/w c) %v/v d) Mol fraction • Argon makes up 0.93% by volume of air. Calculate its solubility (in molars) in water at 20oC and 1.0 atm. (kH of Ar is 1.5x10-3 mol/Latm) • How many grams of NaCl more is needed to prepare a 100.0 mL of 0.1000 molal from 100.0 mL of 0.1000 molar NaCl solution? • How many grams of water must be evaporated from a liter of solution to make a 20%(w/w) MgBr2 to make a 0.0010 molar solution? • You are to prepare 10.0mL 0.0430 M ethanol solution from a stock solution of 20% v/v ethanol. The density of ethanol is 0.789g/mL. How many mL of the stock solution should you use? • Air is 21%(w/w) oxygen. If the molar mass of air is 28.4 grams/mol, calculate the mol ratio of oxygen in the air.