DO NOW: Rank the following phases of matter in order from least to greatest for… A) Energy B) Intermolecular Forces High Energy Medium Energy Low Energy Weak Intermolecular Forces Medium Intermolecular Forces Strong Intermolecular Forces Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441

Phases/States of Matter Gas Shape of Container Volume of Container Solid Liquid ENERGY ENERGY Holds Shape Fixed Volume Shape of Container Free Surface Fixed Volume Solid In a solid the molecules are closely bound to one another by molecular forces. A solid holds its shape and the volume of a solid is fixed by the shape of the solid. Liquid In a liquid the molecular forces are weaker than in a solid. A liquid will take the shape of its container with a free surface in a gravitational field. In microgravity, a liquid forms a ball inside a free surface. Regardless of gravity, a liquid has a fixed volume. Gas In a gas the molecular forces are very weak. A gas fills its container, taking both the shape and the volume of the container

SOLID – e.g. ice Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

LIQUID – e.g. water some writing from Kotz (PowerPoint online) Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

Gas – e.g. steam Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

Some Properties of Solids, Liquids, and Gases Property Solid Liquid Gas Shape Has definite shape Takes the shape of Takes the shape the container of its container Volume Has a definite volume Has a definite volume Fills the volume of the container Arrangement of Fixed, very close Random, close Random, far apart Particles Interactions between Very strong Strong Essentially none particles The three common phases (or states) of matter are gas, liquid, and solid 1. Gases a. Have the lowest density of the three states of matter b. Are highly compressible c. Completely fill any container in which they are placed d. Their intermolecular forces are weak e. Molecules are constantly moving independently of the other molecules present 2. Solids a. Dense b. Rigid c. Incompressible d. Intermolecular forces are strong e. Molecules locked in place 3. Liquids b. Incompressible c. Flow readily to adapt to the shape of the container d. Sum of the intermolecular forces are between those of gases and solids • The state of a given substance depends strongly on conditions

States of Matter Deposition Vaporization Solid, Liquid, Gas are the three states of matter we will deal with. Plasma and Neutron star are also states of matter. For more information about plasma and neutron stars try the following links: Coalition for Plasma Science – What is plasma? http://www.plasmacoalition.org/what.htm Neutron Stars and Pulsars – Introduction http://imagine.gsfc.nasa.gov/cgi-bin/print.pl

release energy and form intermolecular bonds Liquids The two key properties we need to describe are EVAPORATION and its opposite CONDENSATION add energy and break intermolecular bonds EVAPORATION CONDENSATION release energy and form intermolecular bonds

Equilibrium is reached when: Rate of Vaporization = Rate of Condensation Molecules are constantly changing phase - dynamic The total amount of liquid and vapor remains constant

Heating Curve for Water Heating curve with pictures Create a curve!! Heating Curve for Water vaporization E gas D 100 condensation C liquid melting Temperature (oC) Melting, freezing, vaporization, condensation, sublimation, and deposition are six common phase changes. Note: The temperature of a substance does not change during a phase change. B A freezing solid Heat added LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 487

Triple Point Plot melting freezing liquid solid Pressure (atm) vaporization condensation Pressure (atm) 0.6 2.6 sublimation deposition gas Temperature (oC) LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 488

1. Calculate the energy required to melt 8. 5g of ice at 0°C 1.Calculate the energy required to melt 8.5g of ice at 0°C. The molar heat of fusion for ice is 6.02kJ/mol. 2.Calculate the energy in kJ required to heat 25g of liquid water from 25°C to 100°C and change it into steam at 100°C. The specific heat capacity of liquid water is 4.18J/g°C, and the molar heat of vaporization of water is 40.6kJ/mol.

Calculate the energy required to melt 8. 5g of ice at 0°C Calculate the energy required to melt 8.5g of ice at 0°C. The molar heat of fusion for ice is 6.02kJ/mol.

Calculate the energy in kJ required to heat 25g of liquid water from 25°C to 100°C and change it into steam at 100°C. The specific heat capacity of liquid water is 4.18J/g°C, and the molar heat of vaporization of water is 40.6kJ/mol.

Given that the specific heat capacities of liquid water, ice and steam are 4.18J/g°C, 2.06J/g°C & 2.03J/g°C, respectively and considering the molar heats of fusion & vaporization for water are 6.02kJ/mol & 40.6kJ/mol respectively, calculate the total quantity of heat evolved when 10.0 g of steam at 200.°C is condensed, cooled, and frozen to ice at -50°C. (HINT: 5 step problem!)

Intermolecular Forces Irresistible attraction…

ATTRACTIVE FORCES Always electrostatic in nature Intramolecular forces bonding forces These forces exist within each molecule. They influence the chemical properties of the substance. Intermolecular forces nonbonding forces These forces exist between molecules. They influence the physical properties of the substance.

Intermolecular forces (IMF) London dispersion forces: The forces that exist among noble gas atoms and non-polar molecules Dipole-dipole attraction: Molecules with dipole moments (polar molecules) can attract each other by lining up so that the positive and negative ends are close to each other. Hydrogen bonding: when hydrogen is bonded to a highly electronegative -FON Increasing Strength of IMF

Dispersion Force

Examples: CO2, Ar, N2 Dispersion forces among nonpolar molecules. separated Cl2 molecules instantaneous dipoles Examples: CO2, Ar, N2

Increase in MM (molar mass) = Increase in London Dispersion Forces

Dipole–Dipole Attractions Polar molecules have a permanent dipole because of bond polarity and shape dipole moment as well as the always present induced dipole The permanent dipole adds to the attractive forces between the molecules raising the boiling and melting points relative to nonpolar molecules of similar size and shape

Polar molecules and dipole-dipole forces. solid liquid Examples: HF, HCl, NH3

H Bond Video Hydrogen Bonding When a very electronegative atom is bonded to hydrogen, it strongly pulls the bonding electrons toward it O─H, N─H, or F─H Because hydrogen has no other electrons, when its electron is pulled away, the nucleus becomes deshielded exposing the H proton The exposed proton acts as a very strong center of positive charge, attracting all the electron clouds from neighboring molecules

H-Bonding HF

Hydrogen bonding in H2O Surface tension Capillary action Viscosity

Effects of strong intermolecular forces Greater IMF = Increase MP &BP, Decrease in Vapor Pressure