States of Matter

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

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

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

DO NOW: Rank the following phases of matter in order from least to greatest for energy. High Energy Medium Energy Low Energy Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441

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

Thermodynamics Heat: the quantity of energy that flows across the boundary between the system and surrounds because of a temperature difference. Temperature: a measure of the random motions of the components of a substance. Heat Capacity: a measure of the amount of heat needed to change the temperature of a substance by a given amount. Calorimetry: measure of heat flow.

First Law of Thermodynamics The energy in the universe is constant https://cnx.org/resources/389ba2d9eff9ae0848a1ad70edb1d4c3

Calories The amount of energy (heat) required to raise the temperature of one gram of water by one degree Celsius. http://2.bp.blogspot.com/_fXHYJicyyiQ/TUGlC4B3EZI/AAAAAAAAAAM/PZUP-ivN3cs/s1600/doritos-nc.gif https://melielindz.files.wordpress.com/2013/07/cheerios.jpeg

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

Heating Curves http://ch301.cm.utexas.edu/images/heating-curve.jpg

Energy is added/ removed: q3 = mc𝚫T Energy is used for phase change (solid to liquid): 𝚫Hf = 6.01 kJ/mol (for H2O) [qf = m𝚫Hf] Energy is used for phase change (liquid to gas): 𝚫Hv = 40.67 kJ/mol (for H2O) [qv = m𝚫Hv] Energy is added/ removed: q2 = mc𝚫T Energy is added/ removed: q1 = mc𝚫T http://www.kentchemistry.com/images/links/matter/aim10.5.jpg

Phase Diagrams – Definitions Phase Diagram: a graphic way to summarize the conditions under which equilibria exist between the different states of matter Critical Point: the point where the vapor pressure curve ends – this is the critical temperature and critical pressure of the substance Superficial Fluid: the point where the liquid and gas phases become indistinguishable from each other (usually after the critical point) Normal Boiling Point: the boiling point at 1 atm Normal Melting Point: the melting point at 1 atm Triple Point: where the three curves intersect (ie all phases exist at this specific temperature and pressure!)

http://i.stack.imgur.com/HPtp0.png

http://wps.prenhall.com/wps/media/objects/3311/3391416/imag1106/AAAUAZO0.JPG

Sample question: what changes occur as the pressure increases from 1 atm to 60 atm for CO2 at a constant temperature of -60℃? http://wps.prenhall.com/wps/media/objects/3311/3391416/imag1106/AAAUAZP0.JPG

Example Problem Describe the phase changes, if any, between points 1 and 5 using the figure at the right as it relates to temperature and pressure.

Example Problem Describe the phase changes, if any, between points 6 and 9 using the figure at the right as it relates to temperature and pressure.