Accelerated Chemistrychapter 10 Notesmr. Seidel

Accelerated ChemistryChapter 10 notesMr. Seidel

(student edition)

Chapter 10 problems: These problems will be collected and graded for completion and accuracy. Do them on loose-leaf paper – not in your notebook. RC: 3, 8, 9, 12, 14, 15 P: 1, 3, 6, 7 CT: Do any 4

10.1The Kinetic-Molecular Theory of Matter (Gases)

KMT – theory that matter is composed of particles in motion and that motion has consequences.

KMT of gases (ideal gas)

1.

2.

3.

4.

5.

properties of gases resulting from the KTG

expansion - no

fluidity - particles glide past each other ( are both fluids)

low density - gases are roughly the density of solids and liquids

compressibility –

diffusion - spontaneous mixing of 2 substances due to

effusion - a gas spreads through a small opening between containers

Deviations from ideal behavior – Real gases:

a)

b)

Gases that are close to ideal:

Gases that are not close to ideal:

10.2Liquids

Liquids exist in the smallest temperature range, so

liquids are the least common state of matter.

Kinetic theory description of the phases of matter

Properties of liquids:

1. Definite volume

1. Fluidity

1. Relative high density

1. Incompressible

1. Dissolving ability

1. Diffusion

1. Surface tension

1. Evaporation and boiling

10.3Solids

Most elements are solids. All ionic compounds are solids. Solids are the prevalent form of matter as far as possible compounds.

Kinetic description: lower______, less______, IMF ______

Properties of solids:

1. Definite shape and volume2. Non-fluid

1. Definite melting point4. High density

5. Incompressible6. Slow diffusion

Crystalline solids may be classified by a) unit cell or b) binding force

a)a crystal lattice is a collection of unit cells

simplebody centeredface centeredhexagonal

cubic cubic cubic

b)binding force – depends on the particles at the lattice points

Particle / Force / Properties / Example / Drawing

Amorphous solids – examples are ______, ______, ______.

Drawing:Since attractive forces between particles depend on

______, and ______

is ______, there is no ______.

10.4Changes of State

example:

Equilibrium-

Water in an open beakerWater in a closed beaker

Equations:

Le Chatelier’s Principle-

Result: If T ↑,

If T ↓,

Equilibrium Vapor Pressure of a liquid:

Manometer closedManomoter openGraph

Equilibrium vapor pressure depends on:

a)

b)

Example of varying temperature and type of liquid

TemperatureVPwaterVPalcoholVPoil

100 oC

80 oC

50 oC

20 oC

when vapor pressure = atmospheric pressure, the liquid ______!

Demonstration – boiling liquid two different ways

Freezing and melting – involve changes in energy

Solid + heat  liquidand liquid  solid + heat so….

Solid + heat liquid where heat = heat of fusion (Hfus) – for water, Hfus = 6 kJ/mole

melting point and freezing point are exactly the same temperature

At 0 oC, H2O with 6 kJ of heat is a ______

At 0 oC, H2O without 6 kJ of heat is a ______

Heating curve

flat sections at boiling/melting

why? all energy input is directed

at changing phase, so there is no

increase in temperature

3 formulas to use:q = mCpt for sections ______

q = mHfus for section ______

q = mHvap for section ______

Temperature and Phase Change

It is usually assumed that more heat means higher temperature, but not when changing phase.

If a sample of water at 20.0 oC is heated by a hot plate that gives off 250.0 J, how grams of water are in the sample if the temperature rises to 30.0 oC?

remember - Cp H2O (l) =

for ice it’s different because the energy goes into breaking apart the connection between ice molecules that are farther apart when compared with the liquid state. For gas it’s also different. We’ll get chart to tell us the values.

Heat of Vaporization

when....a liquid evaporates, it absorbs energy. Energy is used to overcome attractive forces. The energy doesn’t increase the average energy of the particles, so the temperature doesn’t change.

when...a liquid evaporates, it takes energy from its surroundings that’s why alcohol feels cool to the skin.

it’s also why we get cold when getting out of the shower

Heat of vaporization - Hvap - energy needed to vaporize a unit of substance (mass or moles)

formula q = (H vap ) x ( unit )unit = gram or mole

example - How much heat does it take to vaporize 50.0 g of water at 100.0 C0?

Heat of Fusion

Hfus = heat of fusion - heat required to change a unit of substance from solid to liquid

same formula - q = (Hfus) x (unit)unit = g or mole

example - How much ice can be melted by 2.9 x 104 J?

NIB - putting it all together…

example - How much heat is required (in calories) to transform 50.0 g of ice at - 10.0 degrees Celsius to steam at 110.0 degrees Celsius?

One more phase change… sublimation

Phase diagrams – graphs that indicate the physical state of a substance at a given temperature and pressure.

Most substanceswater

critical temperature - the temperature at which a gas can no longer be liquefied, no matter what the pressure.

critical pressure - the pressure required to liquefy at the critical temperature

10.5 Water–one of the most unusual substances in the universe!

Density Vs Temp.Density Vs Temp.Drawing of H2O

(most substances)(water)(w/ correct geometry)

when H2O molecules line up, they take up more space than they would as a liquid due to..

Other stuff….summing it all up

Theory of Physical Phase - at the same temperature, different substances are in different phases - we learned before that this related to bonds, IMF, and mass

solids - strong attractive forces -______, ______liquids - weaker forces

gases - too weak to stay together, particles bounce off of each other - fill their containers.

The amount of kinetic energy (KE) determines a change in phase

example - If a liquid gets enough energy, particles can change to a gas through evaporation.

reverse - If particles lose enough energy, they can condense into a liquid( )

evaporation happens because some molecules move faster than others and are able to overcome the IMF of the liquid

to increase the rate of evaporation - or

for condensation - do the opposite

condensation raises the temperature of the vapor

evaporation lowers the temperature of the liquid

why? taking out faster or slower moving molecules changes the average temperature

so, why does it feel cool on your forehead when you sweat?

Why does it feel even cooler if a fan is blowing or if there is a breeze?

cooking depends on temperature - a low boil is better than a high boil - cooks just as fast, but uses less fuel

when vapor pressure = atmospheric pressure, the liquid ______.

so ….an alternative to raising temperature is pressure

a pressure cooker increases pressure, so the temperature must rise higher in order to boil

the food cooks at a higher temperature so therefore, it cooks faster.