Changes of State, Phase Diagrams, and Specific Heat
Overview
This section deals with the concept of physical equilibria of chemical systems. Physical equilibria deal with the equilibrium phenomena that does not involve any chemical change. These are instead physical changes like phase changes or (melting of ice intoliquid water) solubility (the dissolving of a solute like sugar in a solvent like liquid water). This section will look at both phase changes of pure substances as well as those of mixtures.
Links to tutorials on Physical Equilibria from the web-based tutorials for GenChem at The University of Texas:
PhaseTransitions
There are number of graphical means to help understand the relationships between the different phases of a particular substance. The first thing we need to do when looking at the transitions to different phases is to establish some definitions.
Heating Curves - Revisited
Heating curves are plots of the temperature of a system as a function of the heat flow into or out of the system.
Phase Diagrams
A phase diagram shows the regions of stability of different phases (i.e. states of matter - solid, liquid, and gas) as a function of temperature and pressure. The interfaces between these regions will be the phase transition equilibium lines.
Triple Point
The triple point is the temperature and pressure at which three phases are in equilibrium.
Critical Point
The critical point is the pressure and temperture above which the substance has the characteristics of a uniquely dense gas.
Vapor Pressure
The vapor pressure of a substance is the partial pressure of that substance in equilibrium with its condensed phase (liquid or solid). The pressure of the vapor over a liquid (or solid) at equilibrium.
Vapor Pressure and Temperature
At higher temperatures the positional states of particles of a substance increases so as to favor higher entropy states tending toward a transition to the gas state.
Claussius-Clapeyron Equation
Using the ideas from the temperature dependence of the vapor pressure we can make a new mathematical relationship that relates the vapor pressure, P1, at one temperature, T1, to the vapor pressure, P2, at another temperature, T2 - this relationship is known as the Claussius-Clapeyron Equation.
Videos by Professor Dave Explains
Thermochemistry: Heat and Enthalpy [4:16] by Professor Dave Explains
What is heat? It's not just a movie with Pacino and DeNiro. Learn all about heat, and more importantly, enthalpy! Energy exchange is a big part of chemistry.
Heat Capacity, Specific Heat, and Calorimetry [4:13] by Professor Dave Explains
We can use coffee cups to do simple experiments to figure out how quickly different materials heat up and cool down.
Phase Changes, Heats of Fusion and Vaporization, and Phase Diagrams [4:50] by Professor Dave Explains
What the heck is dry ice and why is it so spooky? Learn this and more when we investigate phase changes and phase diagrams!
Videos by Bozeman Science
Temperature [4:29] by Bozeman Science
Paul Andersen explains how the temperature is a measure of the average kinetic energy of particles in an object. The temperature is proportional to the average kinetic energy according to the Kelvin scale. At absolute zero there is no molecular motion and it is at 0K.
Heat Exchange [5:04] by Bozeman Science
In this video Paul Andersen explains how energy can be transferred from warmer objects to colder objects through heat. Temperature is a measure of the average kinetic energy of the particles in a substance. When two objects are in contact collisions between the particles will transfer energy from the warmer object in the form of heat.
Conservation of Energy [4:08] by Bozeman Science
Paul Andersen explains how energy can neither be created nor destroyed but may be transferred. Energy comes in many forms (including chemical, mechanical, light, electrical, and thermal). In AP Chemistry students must be accountable for interactions involving an increase in volume over time.
Energy Changing Processes [8:18] by Bozeman Science
Paul Andersen explains how energy can enter and leave a system. The amount of energy a substance can receive through heating or lose through cooling is measured using the specific heat capacity.
Calorimetry [6:00] by Bozeman Science
Paul Andersen describes the history of calorimetry and explains how it can be used to measure energy changes in a system. The specific heat of water is well established and so as a system releases or absorbs energy from a surrounding water bath it can be measured.
Videos by Dr. Mike Christiansen
Thermochemistry: Part 1 of 11 [11:36] by Dr. Mike Christiansen
In this video on thermochemistry and thermodynamics, I’ll teach you the seven polyatomic elements. I’ll also teach you about energy, work, heat, kinetic energy, and potential energy.
Thermochemistry: Part 2 of 11 [7:42] by Dr. Mike Christiansen
In this video on thermochemistry and thermodynamics, Dr. Mike Christiansen continues teaching about kinetic and potential energies by working some specific problems. I’ll also define “systems” (open, closed, and isolated) and “surroundings.”
Thermochemistry: Part 3 of 11 [11:14] by Dr. Mike Christiansen
In this video on thermochemistry and thermodynamics, I’ll teach you the First Law of Thermodynamics. I’ll also teach you the signs and equations for change in energy, change in heat, change in work, and changes in enthalpy. I’ll also teach you the meaning of the terms endothermic and exothermic.
Thermochemistry: Part 7 of 11 [14:11] by Dr. Mike Christiansen
In this video, I’ll show you how to perform specific heat calculations.
Liquids and Intermolecular Forces: Part 4 of 10 [5:20] by Dr. Mike Christiansen
In this video I’ll introduce you to heat curves and dynamic equilibrium. I’ll then teach you how to calculate the final state and temperature of a system at equilibrium, as well as how to calculate, using enthalpy (i.e. heat energy at constant pressure) data, the amount of heat required to convert a substance from one phase to another.
Liquids and Intermolecular Forces: Part 6 of 10 [5:51] by Dr. Mike Christiansen
In this video Dr. Christiansen shows you how to read and interpret phase diagrams, with some accompanying problems. I’ll also tell you about liquid crystals, which are really cool.
Liquids and Intermolecular Forces: Part 9 of 10 [5:49] by Dr. Mike Christiansen
Dr. Christiansen works another problem involving heat curves, enthalpies of fusion, vaporization, phase changes, and the whole gambit.
Liquids and Intermolecular Forces: Part 10 of 10 [2:38] by Dr. Mike Christiansen
In this video Dr. Christiansen will solve some true/false questions involving volatility, boiling points, and intermolecular forces.
Videos by Fus Chemistry Videos
Phase Changes [10:00] by Fus Chemistry Videos
Phase Diagrams [5:38] by Fus Chemistry Videos
The Clausius Clapeyron Equation [5:01] by Fus Chemistry Videos
This section deals with the concept of physical equilibria of chemical systems. Physical equilibria deal with the equilibrium phenomena that does not involve any chemical change. These are instead physical changes like phase changes or (melting of ice intoliquid water) solubility (the dissolving of a solute like sugar in a solvent like liquid water). This section will look at both phase changes of pure substances as well as those of mixtures.
- Adapted from http://ch302.cm.utexas.edu/physEQ/index.php#physical/intro-phys-equil.html
Links to tutorials on Physical Equilibria from the web-based tutorials for GenChem at The University of Texas:
PhaseTransitions
There are number of graphical means to help understand the relationships between the different phases of a particular substance. The first thing we need to do when looking at the transitions to different phases is to establish some definitions.
Heating Curves - Revisited
Heating curves are plots of the temperature of a system as a function of the heat flow into or out of the system.
Phase Diagrams
A phase diagram shows the regions of stability of different phases (i.e. states of matter - solid, liquid, and gas) as a function of temperature and pressure. The interfaces between these regions will be the phase transition equilibium lines.
Triple Point
The triple point is the temperature and pressure at which three phases are in equilibrium.
Critical Point
The critical point is the pressure and temperture above which the substance has the characteristics of a uniquely dense gas.
Vapor Pressure
The vapor pressure of a substance is the partial pressure of that substance in equilibrium with its condensed phase (liquid or solid). The pressure of the vapor over a liquid (or solid) at equilibrium.
Vapor Pressure and Temperature
At higher temperatures the positional states of particles of a substance increases so as to favor higher entropy states tending toward a transition to the gas state.
Claussius-Clapeyron Equation
Using the ideas from the temperature dependence of the vapor pressure we can make a new mathematical relationship that relates the vapor pressure, P1, at one temperature, T1, to the vapor pressure, P2, at another temperature, T2 - this relationship is known as the Claussius-Clapeyron Equation.
Videos by Professor Dave Explains
Thermochemistry: Heat and Enthalpy [4:16] by Professor Dave Explains
What is heat? It's not just a movie with Pacino and DeNiro. Learn all about heat, and more importantly, enthalpy! Energy exchange is a big part of chemistry.
Heat Capacity, Specific Heat, and Calorimetry [4:13] by Professor Dave Explains
We can use coffee cups to do simple experiments to figure out how quickly different materials heat up and cool down.
Phase Changes, Heats of Fusion and Vaporization, and Phase Diagrams [4:50] by Professor Dave Explains
What the heck is dry ice and why is it so spooky? Learn this and more when we investigate phase changes and phase diagrams!
Videos by Bozeman Science
Temperature [4:29] by Bozeman Science
Paul Andersen explains how the temperature is a measure of the average kinetic energy of particles in an object. The temperature is proportional to the average kinetic energy according to the Kelvin scale. At absolute zero there is no molecular motion and it is at 0K.
Heat Exchange [5:04] by Bozeman Science
In this video Paul Andersen explains how energy can be transferred from warmer objects to colder objects through heat. Temperature is a measure of the average kinetic energy of the particles in a substance. When two objects are in contact collisions between the particles will transfer energy from the warmer object in the form of heat.
Conservation of Energy [4:08] by Bozeman Science
Paul Andersen explains how energy can neither be created nor destroyed but may be transferred. Energy comes in many forms (including chemical, mechanical, light, electrical, and thermal). In AP Chemistry students must be accountable for interactions involving an increase in volume over time.
Energy Changing Processes [8:18] by Bozeman Science
Paul Andersen explains how energy can enter and leave a system. The amount of energy a substance can receive through heating or lose through cooling is measured using the specific heat capacity.
Calorimetry [6:00] by Bozeman Science
Paul Andersen describes the history of calorimetry and explains how it can be used to measure energy changes in a system. The specific heat of water is well established and so as a system releases or absorbs energy from a surrounding water bath it can be measured.
Videos by Dr. Mike Christiansen
Thermochemistry: Part 1 of 11 [11:36] by Dr. Mike Christiansen
In this video on thermochemistry and thermodynamics, I’ll teach you the seven polyatomic elements. I’ll also teach you about energy, work, heat, kinetic energy, and potential energy.
Thermochemistry: Part 2 of 11 [7:42] by Dr. Mike Christiansen
In this video on thermochemistry and thermodynamics, Dr. Mike Christiansen continues teaching about kinetic and potential energies by working some specific problems. I’ll also define “systems” (open, closed, and isolated) and “surroundings.”
Thermochemistry: Part 3 of 11 [11:14] by Dr. Mike Christiansen
In this video on thermochemistry and thermodynamics, I’ll teach you the First Law of Thermodynamics. I’ll also teach you the signs and equations for change in energy, change in heat, change in work, and changes in enthalpy. I’ll also teach you the meaning of the terms endothermic and exothermic.
Thermochemistry: Part 7 of 11 [14:11] by Dr. Mike Christiansen
In this video, I’ll show you how to perform specific heat calculations.
Liquids and Intermolecular Forces: Part 4 of 10 [5:20] by Dr. Mike Christiansen
In this video I’ll introduce you to heat curves and dynamic equilibrium. I’ll then teach you how to calculate the final state and temperature of a system at equilibrium, as well as how to calculate, using enthalpy (i.e. heat energy at constant pressure) data, the amount of heat required to convert a substance from one phase to another.
Liquids and Intermolecular Forces: Part 6 of 10 [5:51] by Dr. Mike Christiansen
In this video Dr. Christiansen shows you how to read and interpret phase diagrams, with some accompanying problems. I’ll also tell you about liquid crystals, which are really cool.
Liquids and Intermolecular Forces: Part 9 of 10 [5:49] by Dr. Mike Christiansen
Dr. Christiansen works another problem involving heat curves, enthalpies of fusion, vaporization, phase changes, and the whole gambit.
Liquids and Intermolecular Forces: Part 10 of 10 [2:38] by Dr. Mike Christiansen
In this video Dr. Christiansen will solve some true/false questions involving volatility, boiling points, and intermolecular forces.
Videos by Fus Chemistry Videos
Phase Changes [10:00] by Fus Chemistry Videos
Phase Diagrams [5:38] by Fus Chemistry Videos
The Clausius Clapeyron Equation [5:01] by Fus Chemistry Videos