Aqueous Solutions.

1. Chem Lab 2 Solutions

2. Lab 2.1 Adding Liquids to Water

9. Polar solutes dissolve in polar water. Dipole-dipole attractions form between the polar molecules. The covalent bonds between atoms remain in tact while the attractions between molecules are broken and formed. The ethylene glycol molecules move between the water molecules due to the attractions these molecules.

10. Nonpolar molecules are not attracted to polar water molecules. Like dissolves Like. Nonpolar solutes dissolve in nonpolar solvents. Since the induced dipole attractions between the molecules is relatively weak, random mixing is responsible for the dissolving process.

11. Like dissolves Like

12. The nonpolar iodine dissolved to a small extent in the water. Weak induced dipole-dipole attractions form between the molecules. Upon shaking the iodine leaves the water and becomes dissolved in the nonpolar carbon tetrachloride. Weak induced dipole-induced dipole attractions form between the molecules.

13. Predicting the polarity of a bond Use electronegativity

15. Electronegativity

21. Dipole-dipole attractions form between oppositely charged ends of different polar molecules polar molecule

22. Dipole-dipole attractions form between polar water molecules and polar alcohol molecules. The molecules have moved between each other. The individual molecules remain intact. METHANOL DISSOLVES IN WATER. Notice: The covalent bonds between the atoms remain intact the molecules have simply moved between each other.

23. Dipole-dipole attractions between ethanoic acid molecules. Also known as glacial acetic acid.

25. Polarity and Solubility

27. Oil in water

28. Induced dipole – Induced dipole Attractions Temporary shifts in electron density lead to temporary dipoles

29. Packing peanuts will dissolve in acetone Nonpolar Nonpolar Due to random motion and and mixing (entropy driven- increasing disorder) the molecules mix between each other. Since there is little attraction between any of the molecules, they simple mix Weak induced dipole – induced dipole attractions

30. Styrofoam in acetone Styrofoam in water Is styrofoam polar or nonpolar?

31. Dipole-induced dipole Attractions Polar molecule Nonpolar molecule

33. Listed from strongest IMF to weakest IMF IMF s

37. Memorize these.

38. Hexane

39. Branching chains in alkanes

40. Same attractions (induced dipole-induced dipole attractions) Different states of matter- What difference explains this?

44. ethene ethyne

45. Acteylene torches are used in welding. The combustion of ethyne.

46. Again, notice the difference in boiling points

48. Methanol methanol

49. methanol

50. Alcohol- part polar and part nonpolar

51. Antifreeze- soluble in water due to the polar part Note: two alcohol groups attached

54. Ethanoic Acid Also known as acetic acid or vinegar Ethan- therefore 2 carbons -oic acid add –COOH

57. The longer the nonpolar hydrocarbon chain the less soluble the alcohol more soluble in water less soluble in water

61. Given the same attractions between molecules, size can be used as a predictor of state Differences in Size

67. Which liquid has a higher boiling point? What is the boiling point of each liquid at standard pressure? Normal pressure (1 atm or 760 mm Hg

69. Which liquid has greater attractions between the molecules? If the outside pressure is 200 mmHg what is the BP temp? If the outside pressure is 400 mmHg and the temperature is 10  C, will CS 2 be a liquid or gas?

70. Notice the difference in the axis- pressure compared temperature This is external pressure to show the state given different combinations of pressure and temperature S  ℓ ℓ  g S  g

71. Critical point triple point

73. Lab 2.2 Adding Different Solids to Water

79. Ionic Crystal Lattice

80. The ionic compound has different properties than its elements.

82. Electrolytes conduct electricity in solution.

87. Acid is a substance that produces H + ion (protons) when dissolve in water. HCl, H 2 SO 4 Base is a substance that produces OH - ion (hydroxide) when dissolve in water. NaOH

89. Ions dissociate in solution. Ions are attracted to the oppositely charged ends of water molecules by ion-dipole attractions dipole ion

90. Water- a dipole With two oppositely charged ends Ions attracted to oppositely-charged ends of water molecule ION-DIPOLE ATTRACTION

93. Energy Change Associated with Dissolving Ionic bond break Ion-dipole attractions form Net change +2 kJ/mol Note: the net change in energy +9 kJ/mol Energy absorbed to break ionic bonds Energy released as ion-dipole attractions form

95. Calcium chloride dissolves in water Energy in to break ionic bonds Energy out as ion-dipole attractions form Net change in enthalpy Enthalpy CaCl 2 (s) Ca 2+ (aq) + 2Cl - (aq)

96. Ionic solid with ionic bonds between the ions Water with dipole-dipole attractions between the water molecules Ionic bonds break Ions dissociate Ions move between water molecules Ion-dipole attractions form Solution conducts electricity since charged particles (the ions) are free to move

97. Visualize the solution with ions and water molecules in motion

99. Ammonium nitrate dissolves in water Energy in to break ionic bonds Energy out as ion-dipole attractions form Net change in enthalpy Enthalpy NH 4 NO 3 (s) NH 4 + (aq) + NO 3 - (aq)

101. With a greater positive charge, the Mg 2+ ion is more attracted to the water molecule than Li +1 . Remember: electrical force depends on magnitude of charge- greater charge greater electrical force With a greater size, the K +1 ion cannot get as close to the water molecule as the smaller Li +1 ion. With a lesser distance, the electrical force is greater Remember: electrical force depends on distance- greater distance lesser electrical force

105. Polyatomic Ions Polyatomic ions are charged groups of covalently bonded atoms

106. Formulas and Names for Acids EOS Ternary acids simply use the polyatomic anion name with “ate” changing to “ic” plus the word acid