Bell Ringer (on Thursday) Divide into four groups.

Solids, Liquids, & Gases The States of Matter Unit 8

There are three states (also called phases) of matter. ► The picture to the side represents the same chemical substance, just in different states. en/simulation/states-of- matter-basics en/simulation/states-of- matter-basics

There are three states (also called phases) of matter. ► Solid: Matter that has both a definite shape and definite volume. ► Molecules or atoms are very close together and can only vibrate a little. They do not move past each other.

There are three states (also called phases) of matter. ► Liquid: Matter that has a distinct volume but no specific shape. ► Molecules or atoms are close together but have the ability to slide across one another very easily.

There are three states (also called phases) of matter. ► Gas: matter that has no fixed volume or shape. ► It conforms to the volume and shape of its container. Its molecules or atoms are very far apart from each other and move very fast.

Density Comparison In most cases: ► Solid is more dense than liquid ► Liquid is more dense than gas ► Gas is the least dense

Water is Weird.. Again ► A notable exception is water! The solid state of H 2 O, ice, is less dense than liquid water. This is why ice floats. ► This is true because of the way hydrogen bonds form when liquid water freezes. The hexagonal pattern results in empty space between the molecules.

Two Types of Solids Crystalline Solids ► molecules are packed together in a predictable way. ► They are arranged in an orderly, geometric, three dimensional structure. ► The smallest repeating part of a crystalline structure is called a unit cell. Ex: cubic, hexagonal, rhombohedral, etc.

Two Types of Solids Amorphous Solids: ► particles are NOT arranged in a regular repeating manner. ► Amorphous means “without shape.” ► Glass, rubber, plastics, wax, etc.

Liquids ► Fluidity – liquids (and gases) have the ability to flow.

Liquids ► Viscosity – the measure of the resistance of a liquid to flow. ► Cold pancake syrup is very resistant to flow – it is viscous. ► Water flows easily – it is less viscous.

GasLiquidSolid low density easy to expand/compress fills container high density hard to expand/compress takes shape of container high density hard to expand/compress rigid shape Three States of Matter - Review

Viscosity ► Viscosity decreases with temperature. Ex: heating up the syrup in the microwave makes it pour easier.

Transitions between the 3 states of matter:

Phase Changes That Require Energy (increase in temperature) ► Melting: solid changing to liquid. Ex: ice melting to liquid water ► Vaporization: liquid to gas, occurs when molecules have enough energy to escape the pull of the other molecules. Ex: heating water on the stove, steam is released. ► Sublimation: solid changing directly into gas. Ex: dry ice (solid CO 2 ) lets off CO 2 gas, looks like steam. Solid air fresheners.

Phase Changes that Release Energy (decrease in temperature) ► Condensation: gas to liquid, achieved by removing heat. Ex: “sweat” collects on a cold glass of ice water. ► Freezing: liquid to solid, achieved by removing heat. Ex: water freezing into ice. ► Deposition: gas directly to solid, achieved by removing heat. Ex: frost forms on the grass on a cold morning, snowflakes form from water vapor in clouds.

Equilibrium ► is the state in which two opposing processes are equal. ► Equilibrium is the state in which two opposing processes are equal. ► Equilibrium is reached when the rate of condensation equals the rate of evaporation. ► When a liquid is sealed in a closed container, the liquid evaporates, but at the same time the gas condenses back to the liquid state.

 HEAT CURVE ► The vertical lines are the phases. ► The horizontal plateaus are the phase changes. ► Notice during a phase change the temperature does not change due to heat of fusion and heat of vaporization.

► Fusion (melting): Heat + Solid  Liquid Freezing: Liquid  Solid + Heat ► Enthalpy or Heat of fusion, ∆H fus, heat required to change a given amount of a substance from a solid to a liquid or released when the substance changes from a liquid to a solid ► Vaporization: Heat + Liquid  Gas Condensation: Gas  Liquid + Heat ► Enthalpy or Heat of vaporization, ∆H vap, heat required to change a given amount of a substance from a liquid to a gas or released when the substance changes from a gas to a liquid

Specific Heat Capacity Specific heat is the a mount of heat needed to raise the temperature of 1 g of a substance by 1° C or 1 K. Specific heat is the a mount of heat needed to raise the temperature of 1 g of a substance by 1° C or 1 K. Q = m c ΔT Q = m c ΔT Energy Released/Absorbed = mass x specific heat x temp. change ► Unit for c = J/g°C

 HEAT CURVE ► Since Temperature is a measure of "Average Kinetic Energy", any change in temperature is a change in Kinetic Energy. ► Since temperature does not change during a phase change, the energy that is gained or lost is Potential Energy.

► Heat Curve lab you were suppose to do.

PHASE DIAGRAM   HEAT CURVE