Active Active ChemistryChemistry

Kinetic Kinetic MoleculaMolecular Theory r Theory and the and the Gas Gas LawsLaws

Phases of MatterPhases of MatterThere are four phases of matter:There are four phases of matter:

1. Solid1. Solid

2. Liquid2. Liquid

3. Gas3. Gas

4. Plasma4. Plasma

The state of matter depends on the The state of matter depends on the motion of the molecules that make it up.motion of the molecules that make it up.

SolidsSolids

Solids are objects that have definite shapes and volumes. Solids are objects that have definite shapes and volumes. The atoms or molecules are tightly packed, so the solid The atoms or molecules are tightly packed, so the solid keeps its shape. The arrangement of particles in a solid keeps its shape. The arrangement of particles in a solid are in a regular, repeating pattern called a crystal.are in a regular, repeating pattern called a crystal.

Microscopic picture of a solid.

LiquidsLiquids

The particles in a liquid are close together, but are The particles in a liquid are close together, but are able to move around more freely than in a solid. able to move around more freely than in a solid. Liquids have no definite shape and take on the Liquids have no definite shape and take on the shape of the container that they are in.shape of the container that they are in.

Microscopic picture of a liquid.

GasesGases

A gas does not have a definite shape or volume. A gas does not have a definite shape or volume. The particles of a gas have much more energy The particles of a gas have much more energy than either solids or liquids and can move than either solids or liquids and can move around freely.around freely.

Microscopic picture of a gas.

PlasmaPlasmaPlasma is a gas-like mixture of positively and Plasma is a gas-like mixture of positively and

negatively charged particles. It is found in stars, negatively charged particles. It is found in stars, such as the sun, and in fluorescent lighting. such as the sun, and in fluorescent lighting. Plasma occurs when temperatures are high Plasma occurs when temperatures are high enough to cause particles to collide violently and enough to cause particles to collide violently and be ripped apart into charged particles.be ripped apart into charged particles.

Postulates of KMTPostulates of KMT

A gas consists of a collection of small particles A gas consists of a collection of small particles traveling in straight-line motion. traveling in straight-line motion. The molecules in a gas occupy no volume (that is, The molecules in a gas occupy no volume (that is, they are points spread far apart).they are points spread far apart).Collisions between molecules are perfectly elastic Collisions between molecules are perfectly elastic (that is, no energy is gained or lost during the (that is, no energy is gained or lost during the collision). collision). There are no attractive or repulsive forces between There are no attractive or repulsive forces between the molecules. the molecules. The average kinetic energy of a molecule is The average kinetic energy of a molecule is proportional to the Temperature.proportional to the Temperature.Molecules can collide with each other and with the Molecules can collide with each other and with the walls of the container. Collisions with the walls walls of the container. Collisions with the walls account for the pressure of the gas.account for the pressure of the gas.

At the same temperature, lighter gases At the same temperature, lighter gases move faster than heavier gases.move faster than heavier gases.

TemperatureTemperature

Temperature is a measure of the amount of the Temperature is a measure of the amount of the average kinetic energy of the particles in matter. average kinetic energy of the particles in matter. The more kinetic energy the particles have, the The more kinetic energy the particles have, the higher the temperature.higher the temperature. The temperature of The temperature of particles are usually recorded in one of three particles are usually recorded in one of three ways:ways:

1. Fahrenheit (1. Fahrenheit (ºF)ºF)

2. Celsius (2. Celsius (ºC)ºC)

3. Kelvin (K) **3. Kelvin (K) **SI unit!!!SI unit!!!

FahrenheitFahrenheit

Developed by Daniel Gabriel Fahrenheit, who is Developed by Daniel Gabriel Fahrenheit, who is best known for inventing the alcohol best known for inventing the alcohol thermometer and mercury thermometer in the thermometer and mercury thermometer in the early 1700’s. It is based on 32early 1700’s. It is based on 32º for the freezing º for the freezing point of water and 212º for the boiling point of point of water and 212º for the boiling point of water. The interval between the freezing and water. The interval between the freezing and boiling points are divided into 180 parts. boiling points are divided into 180 parts.

The conversion to Fahrenheit is: ºThe conversion to Fahrenheit is: ºF = (9/5F = (9/5ººC) + C) + 3232

CelsiusCelsius

Scale developed by Anders Celsius in the early to mid-Scale developed by Anders Celsius in the early to mid-1700’s, working from the invention of Fahrenheit's 1700’s, working from the invention of Fahrenheit's thermometers. The Celsius scale is based on 0thermometers. The Celsius scale is based on 0º for º for the freezing point of water and 100º as the boiling the freezing point of water and 100º as the boiling point. The interval between the freezing and boiling point. The interval between the freezing and boiling points are divided into 100 parts.points are divided into 100 parts.

The conversion to Celsius is: The conversion to Celsius is:

ºC= (5/9)(ºF-32)ºC= (5/9)(ºF-32)

ºC= K-273ºC= K-273

KelvinKelvinDeveloped by William Thompson Kelvin in 1848, KelvinDeveloped by William Thompson Kelvin in 1848, Kelvin

isis a temperature scale having an absolute zero below a temperature scale having an absolute zero below which temperatures do not exist. At 0K, all molecules which temperatures do not exist. At 0K, all molecules cease any type of motion (as in the temperature of cease any type of motion (as in the temperature of outer space). It corresponds to a temperature of -outer space). It corresponds to a temperature of -273°C. The Kelvin degree is the same size as the 273°C. The Kelvin degree is the same size as the Celsius degree, so the freezing point of water is at Celsius degree, so the freezing point of water is at 273K and the boiling point is at 373K.273K and the boiling point is at 373K.

The conversion to Kelvin is: K=ºC +273The conversion to Kelvin is: K=ºC +273

Temperature Conversions Temperature Conversions

Ex. 1: The boiling point of Liquid Nitrogen is –1950C, what is the temperature in Kelvin?

Formula: K = 0C + 273

K = -195 + 273 = 78.0 K (3 Sig Dig)

Temperature ConversionsTemperature Conversions

Ex. 2 The normal body temperature is 310. K, what is it in Celsius?

Formula: 0C = K - 273

0C = 310. – 273 = 37.0 0C

Temperature and Volume

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Volume and TemperatureVolume and Temperature

Pressure and the # of particles are constant thenPressure and the # of particles are constant then

As Temperature As Temperature decreasesdecreases, Volume _________ , Volume _________

ororAs Temperature As Temperature increasesincreases, Volume __________, Volume __________

This is a relationshipThis is a relationshipdirect

decreases

increases

Charles’ Law Example Charles’ Law Example A quantity of gas occupies a volume of 506 cmA quantity of gas occupies a volume of 506 cm33 at a temperature of 147at a temperature of 147ooC. Assuming that the C. Assuming that the pressure remains constant, at what pressure remains constant, at what temperature will the volume of the gas be 604 temperature will the volume of the gas be 604 cmcm33??

VV11 = 506cm = 506cm33 VV22= 604cm= 604cm33

TT11 = 147 = 147ooC + 273 =C + 273 = 420K420K TT22= ??= ??

A Graph of Charles’s LawA Graph of Charles’s Law

Charles LawCharles Law

If n (moles) and P are constant, If n (moles) and P are constant,

then V then V αα T T

V and T are directly proportional.V and T are directly proportional.

If one temperature goes up, the volume If one temperature goes up, the volume goes up!goes up!

VV11 VV22

TT11 T T22

=

Jacques Charles Jacques Charles (1746-1823)(1746-1823)

Charles’ LawCharles’ LawDoubling the Kelvin temperature of a gas Doubling the Kelvin temperature of a gas makes the gas expand resulting in makes the gas expand resulting in doubling the volume of the gasdoubling the volume of the gas