# States of matter and thermodynamics

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States of matter and thermodynamics

Solid Does not flow. Definite shape. Definite volume.

Liquid It flows. Takes on the shape of its container.
Has a definite volume.

Gas It flows. Takes on the shape of its container
Has NO definite volume. Always fills the container it’s in.

pHet States of Matter Lab

4/7/11 – “C” Day Objective: To understand the relationships between pressure, temperature, and kinetic energy. Do Now: Sketch a graph showing the relationship between Temperature and Kinetic Energy of Particles. Where would you place a solid, liquid and a gas on this graph? Today: Complete Test Corrections Complete Phet States of Matter Activity Intermolecular Forces - HW

4/8/11 – “D” Day Objective: To understand the relationships between pressure, temperature, and kinetic energy. Do Now: In our Weblab – Why did some particles stick together and others not? What do you think this did to the temperature needed to turn from a solid  liquid or liquid  gas? Today: Collect Intermolecular Forces – HW Discuss Phet States of Matter Activity States of Matter Notes Gases Lab

Kinetic theory and phases of matter
Kinetic theory – all matter is made up of tiny particles that are constantly in motion. Remember kinetic = motion Energy is Directly Related to Temperature Remember q (heat or energy) = mcΔT

What determines if something is a solid, liquid or gas?
Temperature Pressure Intermolecular Forces

Temperature Average KE per molecule in a substance.
Measure w/ thermometer. Alcohol in thermometer expands as it is heated. Units: Fahrenheit Celsius Kelvin

Temperature Temperature is related to the random motion of atoms & molecules in a substance. (Molecules will refer to : atoms & molecules) ↑ Temp = ↑ average KE of molecules ↓ Temp = ↓ average KE of molecules

Temperature Q: Consider 1L vs 2L of boiling water. Which has a higher temperature? A: Same temp. Average KE of molecules is the same.

Absolute Zero Temp has no upper limit. Stars (plasma): MANY MILLION °C
Absolute Zero- Nature’s lowest possible temperature. 0 Kelvin = -273 ° C Molecules lost all available KE. No motion No more E can be removed…. Can’t get any colder than this!

Heat and temperature Heat- the thermal energy transferred from one substance to another due to a temperature difference (Av. KE) between the molecules of two substances.

Heat and Temperature Temperature is the average kinetic energy in a system Heat is the transfer of energy between objects because of the difference in temperature Heat transfers spontaneously from hot to cold

Which has the higher temperature, 1 L or 2 L of boiling water?
Which has more energy?

Intermolecular Forces
Attraction between particles Ionic bonds Hydrogen bonds Van der waal’s forces

Ionic bonds Ionic compounds are not arranged in molecules, but instead form large crystals held together by ionic bonds. Charge on ions provides attraction.

Hydrogen bonds Covalent molecules form solids when intermolecular forces are great enough to hold molecules together, usually as a crystal. Strongest intermolecular force is hydrogen bonding, between the H of one molecule, and an N, O or F of another. These molecules are very polar and have strong + and - ends

Water – example of H bonds
The dashed lines are the hydrogen bonds in an ice crystal

Van der waal’s forces Other molecules are attracted by weaker dipole and London dispersion forces. These forces are also between positive and negative ends of a molecule, but the charges are usually much smaller than in hydrogen bonds.

Dipole-Dipole

Solids Held together by intermolecular forces in highly organized patterns. Dense and incompressible Do not flow

Liquids Intermolecular forces hold particles together, but particles are not locked in place. Can move freely through the liquid. This allows the liquid to flow, but keeps the volume constant.

Gases Particles in constant rapid motion, independent of each other. Gases are not held together by intermolecular forces, do not have a constant shape or volume

Liquids and Kinetic Theory
Liquids have three properties that relate to the Kinetic Theory: Evaporation Vapor pressure Boiling point

Evaporation Remember, temperature is a measure of the average kinetic energy. Some particles have more kinetic energy Particles with a high enough kinetic energy can break free from the surface and become a gas

Vapor Pressure In a closed system, molecules move back and forth between liquid and gas.

Vapor pressure The vapor pressure is a measure of how much gas there is at a given temperature. The higher the temperature, the higher the vapor pressure

Boiling point Boiling occurs at specific temperatures and pressures. Pockets of gas form in the liquid as bubbles and move to the surface.

Boiling point When the vapor pressure equals the atmospheric pressure the liquid boils

Changes of state Solid to liquid – melting Liquid to solid – freezing
Liquid to gas – evaporation Gas to liquid – condensation Solid to gas - sublimation

Construct a heating curve for water
Heating curve lab

Heating curve What is happening between B and C?

Heat of Fusion Energy required to go from a solid to a liquid
at the same temperature. Between B and C, energy is being used to melt the material

Heat of Fusion 100/18 = 5.6 moles 5.6 moles *6.01kJ/1 mole = 33.66 kJ
How many Joules are required to melt 100 g of ice at 0°C? Heat of fusion for water is 6.01kJ/mole How many moles of water is 100g? 100/18 = 5.6 moles 5.6 moles *6.01kJ/1 mole = kJ

What is happening between D and E?

Heat of vaporization Energy required to go from a liquid to a solid
at the same temperature. Between D and E, energy is being used to evaporate (boil) the material

Heat of vaporization 150/18 = 8.3 moles
How many Joules are required to convert 150 g of water at 100°C to steam? Heat of vaporization for water is 40.67kJ/mole How many moles of water is 150g? 150/18 = 8.3 moles 8.3 moles *40.67kJ/1 mole = kJ

Sublimation Under certain conditions, a material can go directly from a solid to a gas. This is called sublimation. Air freshener mini lab

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