2.  Has fixed volume  Has fixed shape  Molecules are held in specific locations  by electrical forces  vibrate about equilibrium positions  Can be modeled as springs connecting molecules

3.  Atoms have an ordered structure  This example is salt  Red spheres represent Na + ions  Blue spheres represent Cl - ions  Atoms are arranged randomly  Examples include glass

4.  Has a fixed volume  No fixed shape  Exist at a higher temperature than solids  The molecules “wander” through the liquid in a random fashion  The intermolecular forces are not strong enough to keep the molecules in a fixed position

5.  Has no fixed volume  Has no fixed shape  Molecules are in constant random motion  The molecules exert only weak forces on each other  Average distance between molecules is large compared to the size of the molecules

6.  Matter heated to a very high temperature  Many of the electrons are freed from the nucleus  Result is a collection of free, electrically charged ions  Plasmas exist inside stars

7.  Internal Energy, U, is the TOTAL energy associated with the microscopic components of the system  Includes kinetic and potential energy associated with the random translational, rotational and vibrational motion of the atoms or molecules  Also includes the intermolecular potential energy  Heat (thermal energy) is a mechanism by which energy is transferred between a system and its environment because of a temperature difference between them  The sum of the KE of all of the molecules in the sample of the substance

9. Heat or thermal energy flows from the warmer object to the cooler object until the objects reach the same temperature 50 o F40 o F43 o F The flow of thermal energy ceases when the objects reach the same temperature. This is known as thermal equilibrium.

10.  Calorie  An historical unit, before the connection between thermodynamics and mechanics was recognized  A calorie is the amount of energy necessary to raise the temperature of 1 g of water from 14.5° C to 15.5° C. (1 o C)  A Calorie (food calorie) is 1000 cal  1 cal = 4.186 J  This is called the Mechanical Equivalent of Heat  The Joule is the SI unit of energy

11. A measure of the Average Kinetic Energy (KE) of all of the particles in an object 1.Fahrenheit ( o F)- standard scale in the U.S., but not anywhere else 2.Celsius ( o C)- standard scale everywhere else 3.Kelvin (K) – standard scale in scientific research 4.Rankien ( o R)- F scale that starts at zero Temperature scales – have 2 fixed points (usually the melting and boiling points of water)

12.  Thermometers are devices used to measure the temperature of an object or a system  Mercury (now alcohol) thermometer is an example of a common thermometer

13.  Temperature of an ice-water mixture is defined as 0º C  This is the freezing point of water  Temperature of a water-steam mixture is defined as 100º C  This is the boiling point of water  Distance between these points is divided into 100 segments

14.  All gases extrapolate to the same temperature at zero pressure  This temperature is absolute zero

15.  When the pressure of a gas goes to zero, its temperature is –273.15º C  This temperature is called absolute zero  This is the zero point of the Kelvin scale  0 K = –273.15º C (or rounded to -273)  To convert: T K = T C + 273

16.  Some representative Kelvin temperatures  Note, this scale is logarithmic  Absolute zero has never been reached

18.  The density of a substance of uniform composition is defined as its mass per unit volume:  Units are kg/m 3 (SI) or g/cm 3 (cgs)  1 g/cm 3 = 1000 kg/m 3

19.  The densities of most liquids and solids vary slightly with changes in temperature and pressure  Densities of gases vary greatly with changes in temperature and pressure

20.  Thermostats  Use a bimetallic strip  Two metals expand differently

21.  At the temperature of water increases from 0ºC to 4 ºC, it contracts and its density increases  Above 4 ºC, water exhibits the expected expansion with increasing temperature  Maximum density of water is 1000 kg/m 3 at 4 ºC

22.  Every substance requires a unique amount of energy per unit mass to change the temperature of that substance by 1° C  The specific heat, c, of a substance is a measure of this amount  SI units  J kg -1 °C -1  Historical units  cal g -1 °C -1

23.  When a fixed mass of a substance requires a certain amount of heat to raise its temperature by 1° C  For example, 10 kg of Iron will have a different thermal capacity than 20 kg of Iron  The thermal capacity (C) of a body is a measure of this amount of heat  SI unit  J °C -1

24.  Q = m c Δ T  Δ T is always the final temperature minus the initial temperature  When the temperature increases, Δ T and Δ Q are considered to be positive and energy flows into the system  When the temperature decreases, Δ T and Δ Q are considered to be negative and energy flows out of the system

25.  Water has a high specific heat compared to land  On a hot day, the air above the land warms faster  The warmer air flows upward (is less dense) and cooler air (more dense) moves toward the beach

26.  One technique for determining the specific heat of a substance  A calorimeter is a vessel that is a good insulator that allows a thermal equilibrium to be achieved between substances without any energy loss to the environment

27.  Analysis performed using a calorimeter  Conservation of energy applies to the isolated system  The energy that leaves the warmer substance equals the energy that enters the water  Q cold = -Q hot Heat lost by 1 substance= Heat gained by another substance  Since Q = mc  T, we could then state that m 1 c 1  T 1 = m 2 c 2  T 2

28.  A phase change occurs when the physical characteristics of the substance change from one form to another  Common phases changes are  Solid to liquid – melting  Liquid to gas – boiling  Liquid to solid- freezing  Gas to liquid- condensing  Solid to gas- sublimation  Phases changes involve a change in the internal energy, but no change in temperature

29.  During a phase change, the amount of heat is given as Q = m L  L is the latent heat of the substance (latent means hidden or concealed)  During melting and boiling, added energy does not cause an increase in temperature, so the (average) KE of the molecules stays constant. This added energy increases the PE of the molecules.  The PE of the molecules would decrease during freezing and condensing Latent heat of fusion is used for melting or freezing Latent heat of vaporization is used for boiling or condensing

30.  During evaporation, the faster moving (more KE) molecules at a liquid’s surface escape into the gas phase.  When this happens, the temperature of the remaining liquid decreases.  Boiling takes place throughout the entire liquid.  Boiling always takes place at the same temperature (at a given pressure).

32.  Start with one gram of ice at – 30.0º C  During A, the temperature of the ice changes from – 30.0º C to 0º C  Use Q = m c Δ T

33.  Once at 0º C, the phase change (melting) starts  The temperature stays the same although energy is still being added  Use Q = m L f

34.  Between 0º C and 100º C, the material is liquid and no phase changes take place  Energy added increases the temperature  Use Q = m c Δ T

35.  At 100º C, a phase change occurs (boiling)  Temperature does not change  Use Q = m L v

36.  After all the water is converted to steam, the steam will heat up  No phase change occurs  The added energy goes to increasing the temperature  Use Q = m c Δ T