To learn about interactions among water molecules Objectives To learn about hydrogen bonding, dipole-dipole, and London dispersion forces (van der Waals) To understand the effect of intermolecular forces on the properties of liquids To learn about interactions among water molecules To predict relative physical properties based on intermolecular forces of attraction

A. Intermolecular Forces Reviewing what we know Gases Solids Low density Highly compressible Fill container High density Slightly compressible Rigid (keeps its shape)

Intermolecular forces – occur between molecules (Red Rover holding hands) Intramolecular forces – occur inside the molecules (bonds)

Occurs between H and highly electronegative atom Hydrogen Bonding (STRONGEST OF 3) Highly Magnetic Highly Polar Molecule (Not really a Bond) (Adhesion disk demo) Occurs between H and highly electronegative atom For example H-N, H-O, H-F bond

Dipole – Dipole attraction (Middle Strength) Permanent Magnetic Properties related to molecular dipole moment Polar Molecules

London Dispersion Forces (van der Waals) Weakest-sometimes magnet-NonPolar Molecules Formation of instantaneous dipoles by location of electrons in orbital

A. Intermolecular Forces London Dispersion Forces (van der Waals) Found in Nonpolar molecules

A. Intermolecular Forces The nature of intermolecular forces is the same as the nature of intramolecular forces (bonds) – only to a varying degree. Intermolecular forces of attraction are a weaker part of the continuum of magnetic attractive forces that include chemical bonding. Weaker (Inter) (Intra) Stronger ______________________________________ VDW D-D H-Bond Covalent Polar Ionic

A. Intermolecular Forces H bonding molecules will exhibit all 3 intermolecular forces of attraction H Bonding forces will be the dominate D-D molecules will exhibit D-D and vdW vdW only vdW

VDW Dipole – Dipole H-Bonding sometimes Magnet Non Polar Weak IMF A. Summary of IMF Forces VDW Dipole – Dipole H-Bonding sometimes Magnet Non Polar Weak IMF

Draw L-D and predict polarity to determine which type of IMF will dominate. NH3 HCl BCl3 CH3Cl CH4 H2O H2S HF

A. Intermolecular Forces London Dispersion Forces Become stronger as the sizes of atoms or molecules increase ---WHY? As atomic size increases, what else increases in number? How would this affect the ability of the molecules to pull together? FP?

A. Intermolecular Forces Hydrogen Bonding Affects physical properties Boiling point Which molecule has the strongest Intermolecular forces of attraction? Why?

A. Intermolecular Forces Pour CH3OH vs H2O on tabletop The strength of intermolecular forces of attraction and the ability of the molecules to hold together directly affect the temperature at which substances melt (or freeze) and boil (or condense). See the Heating Curve…Explain on a molecular level what happens during the solid/liquid and liquid/gas phase change…..

B. Water and Its Phase Changes Heating/cooling curve

B. Water and Its Phase Changes Normal boiling point – at 1 atm = 100oC Normal freezing point – at 1 atm = 0oC Density Liquid = 1.00 g/mL Solid = 0.917 g/mL Density differs because of the H-bonding effect at lower temps (lattice) (vdW, DD, H videos)

B. Water and Its Phase Changes Let’s consider what happens on a molecular level when a substance changes phase from solid to liquid and liquid to gas. Motion, space between molecules, forces to overcome? Changes of state video Thoughts on boiling water at room temperature? Thoughts only!!

B. Water and Its Phase Changes As the strength of the intermolecular forces increases: The Boiling Point increases The Vapor Pressure decreases The Freezing Point increases

B. Predicting Relative Physical Properties Which of the following substances would have the higher boiling point? (Think polarity) NH3 or BCl3 CH4 or CH3Cl H2O or H2S HF or HCl Which would have the highest freezing point? Vapor Pressure?

B. Predicting Relative Physical Properties

To learn about interactions among water molecules Objectives Review To learn about hydrogen bonding, dipole-dipole, and London dispersion forces (van der Waals) To understand the effect of intermolecular forces on the properties of liquids To learn about interactions among water molecules To predict relative physical properties based on intermolecular forces of attraction Work Session: Page 497 Review # 1-5

To understand and use heat of fusion and heat of vaporization Objectives To understand and use heat of fusion and heat of vaporization To derive formulas To use the 5 Step Method to find solutions using multiple equations

C. Energy Requirements for the Changes of State Calculate the heat required to raise 9.54 g of liquid water from a temperature of 0 oC to 80 oC? The specific heat capacity of liquid water is 4.18 . Q = ms T Q = ? m = 9.54 g s = 4.18 T = (80 – 0) oC

C. Energy Requirements for the Changes of State Calculate the heat required to raise 9.54 g of liquid water from a temperature of 0 oC to 80 oC? The specific heat capacity of liquid water is 4.18 . Q = ms T Q = (9.54 g) (4.18 )(80 – 0) oC Q = 3190.18 J = 3.19 kJ Remember this #

C. Energy Requirements for the Changes of State Changes of state are physical changes No chemical bonds are broken

C. Energy Requirements for the Changes of State Molar heat of fusion – energy required to melt (S-L) 1 mol of a substance Molar heat of vaporization – energy required to change 1 mol of a liquid to its vapor …units of both??

C. Energy Requirements for the Changes of State If the molar heat of fusion of ice is 6.02 kJ/mol, how much energy is required to melt 9.54 g of ice at 0 oC? Can we derive the formula? Q = (molar heat of fusion kJ/mol)(mol) Q = fusion = mol =

If the molar heat of fusion of ice is 6 If the molar heat of fusion of ice is 6.02 kJ/mol, how much energy is required to melt 9.54 g of ice at 0 oC? Q = (molar heat of fusion kJ/mol)(mol) Q = ? fusion = 6.02 kJ/mol mol = 9.54 g = mol Q = (6.02 kJ/mol)(0.53mol) = 3.19 kJ Same Q to change phase S-L as to heat 80 oC!

C. Energy Requirements for the Changes of State Calculate the energy (kJ) required to heat 25 g of liquid water from 25 oC to 100 oC and change it to steam at 100 oC. The specific heat capacity of liquid water is 4.18 , and the molar heat of vaporization of water is 40.6 kJ/mol. _____________________________________ Make a mental map- what is the essential Q? Gather what you know- formulas, constants? Unit analysis-conceptual logic, what’s going on?

C. Energy Requirements for the Changes of State Calculate the energy (kJ) required to heat 25 g of liquid water from 25 oC to 100 oC and change it to steam at 100 oC. The specific heat capacity of liquid water is 4.18 , and the molar heat of vaporization of water is 40.6 kJ/mol. Energy in kJ to take Liq from 25 oC to steam at 100 oC 1) Warm w/o phase change 2) phase change Two formulas, two thermodynamic properties

C. Energy Requirements for the Changes of State Calculate the energy (kJ) required to heat 25 g of liquid water from 25 oC to 100 oC and change it to steam at 100 oC. The specific heat capacity of liquid water is 4.18 , and the molar heat of vaporization of water is 40.6 kJ/mol. 1) Warm: Q = ms T Q = m = s = T =

C. Energy Requirements for the Changes of State 1) Warm: Q = ms T Q = ? m = 25 g s = 4.18 T = (100 – 25) oC Q = ms T = (25 g)(4.18 )(75 oC) = 7.8 X 103 J 7800 J = kJ 7.8 kJ Warm only……

C. Energy Requirements for the Changes of State Calculate the energy (kJ) required to heat 25 g of liquid water from 25 oC to 100 oC and change it to steam at 100 oC. The specific heat capacity of liquid water is 4.18 , and the molar heat of vaporization of water is 40.6 kJ/mol. 2) Phase change Q = (molar heat of vap kJ/mol)(mol) Q = ? vap = 40.6 kJ/mol mol = 25 g = mol Q = (40.6 kJ/mol)(1.39 mol) = 56.43 kJ

C. Energy Requirements for the Changes of State Calculate the energy (kJ) required to heat 25 g of liquid water from 25 oC to 100 oC and change it to steam at 100 oC. The specific heat capacity of liquid water is 4.18 , and the molar heat of vaporization of water is 40.6 kJ/mol. 1) Warm = 7.8 kJ 2) Phase change = 56.43 kJ Total ------------------ = 64.23 kJ Notice that most of the energy is required for the phase change event.

C. Energy Requirements for the Changes of State molar heat of vaporization of water is 40.6 kJ/mol molar heat of fusion of water is 6.02 kJ/mol Does it take more energy to melt ice or boil liquid? Why?

To understand and use heat of fusion and heat of vaporization Objectives Review To understand and use heat of fusion and heat of vaporization To derive formulas To use the 5 Step Method to find solutions using multiple equations Work Session: Page 497 #6-7 Practice Problem 14.2

To relate the boiling point of water to its vapor pressure Objectives To understand the relationship among vaporization, condensation and vapor pressure To relate the boiling point of water to its vapor pressure To predict relative physical properties based on intermolecular forces of attraction

A. Evaporation and Vapor Pressure Vaporization or evaporation – individual molecules gain enough energy to change phase Endothermic – requires heat input (Sanitizer)

A. Evaporation and Vapor Pressure Amount of liquid first decreases then becomes constant - H2O bottle Condensation - process by which vapor molecules convert to a liquid When no further change is visible the opposing processes balance each other - equilibrium

A. Evaporation and Vapor Pressure Vapor pressure - pressure of the vapor present at equilibrium with its liquid Vapor pressures vary widely - relates to intermolecular forces

A. Evaporation and Vapor Pressure Vapor pressure - pressure of the vapor present at equilibrium with its liquid- relates to intermolecular forces Molecules with higher intermolecular forces of attraction will have ________ vapor pressures because _________________________. lower, molecules will hold together more.

A. Evaporation and Vapor Pressure Which of the following substances would have the higher vapor pressure? Why? NH3 or BF3 CH4 or CH2Cl2 H2O or CH3OH (methyl alcohol) CH3OH or CH3CH2CH2CH2OH (butyl alc) What is the BP of methyl alcohol? Butyl alc?

B. Boiling Point and Vapor Pressure

B. Boiling Point and Vapor Pressure

B. Boiling Point and Vapor Pressure Boiling point is defined as occurring when the vapor pressure of the liquid is equal to the total external pressure (atmospheric pressure). Not defined by temperature! Boil water at room temp?? Boil water with ice?

B. Boiling Point and Vapor Pressure Which of the following substances would have the higher……BP FP VP GeH4 or AsH3 CCl4 or H2Te CO2 or H2S HF or HBr The amazing floating steel!

To relate the boiling point of water to its vapor pressure Objectives Review To understand the relationship among vaporization, condensation and vapor pressure To relate the boiling point of water to its vapor pressure To predict relative physical properties based on IMF’s To reiterate the difference between IMF and bonds Work Session: Page 503 # 1, 2, 4, 5, 6

To learn about the types of crystalline solids Objectives To learn about the types of crystalline solids To understand the interparticle forces in crystalline solids To learn how the bonding in metals determines metallic properties

A. The Solid State: Types of Solids Crystalline solids

A. The Solid State: Types of Solids

A. The Solid State: Types of Solids

B. Bonding in Solids

B. Bonding in Solids Ionic Solids Stable substances with high melting points Held together by strong forces between ions

B. Bonding in Solids Molecular Solids Fundamental particle is a molecule Melt at relatively low temperatures Held together by weak intermolecular forces

B. Bonding in Solids Atomic Solids Fundamental particle is the atom Properties vary greatly Group 8 - low melting points Diamond - very high melting point

B. Bonding in Solids Bonding in Metals Metals are held together by nondirectional covalent bonds (called the electron sea model) among the closely packed atoms Video clips?

B. Bonding in Solids Bonding in Metals Metals form alloys of two types Substitutional – different atoms are substituted for the host metal atoms

B. Bonding in Solids Bonding in Metals Metals form alloys of two types Interstitial – small atoms are introduced into the “holes” in the metallic structure