GASES

PROPERTIES OF GASES

Gases are compressible.Gases fill any container that they occupy.

Gases expand in the heat.Gases do not settle in their container.

KINETIC MOLECULAR THEORY OF GASES

A gas consists of very small particles. The particles are in constant, random, straight-line motion.

The molecules of a gas are very far from each other relative to their size.

There is no interaction between molecules, they act independently of each other.

Molecules collide with each other and with the walls of the container in a perfectly elastic manner.

PRESSURE= force exerted per unit areaP = F/A = N/m2 = Pa= Blaise Pascal

COMMON UNITS OF PRESSURE

Units Symbol Equivalent to 1 atm

Atmosphere atm     1 atm

Millimeter of Mercury

mmHg            760 mmHg

Torr Torr        760 Torr

Pascal Pa           101326 Pa

Kilopascal kPa*             101.326 kPa

Bar bar             1.01325 bar

Millibar mb             1013.25 mb

Pounds per square inch

psi 14.7 psi

EVANGELISTA TORRICELLI

TEMPERATURE-William Thomson/ Lord Kelvin

- 0 K = - 273 0C- K = 0C + 273

STP/ STANDARD TEMPERATURE AND PRESSURE

0 0C 1 atm 760 mm Hg

760 torr

GAS LAWS

Boyle’s Law

Gay- Lussac’s

Law

Dalton’s Law of Partial

PressureCharles’

LawAvogadro’s

LawGrahams Law of Effusion

Combined Gas Law

Ideal Gas Law

BOYLE’S LAW - Robert Boyle

P ά 1/VP1V1 = P2V2

Constant Variable:

T, n

A TANK OF NITROGEN HAS A VOLUME OF 14.0 L AND A PRESSURE OF 760 MM HG. FIND THE VOLUME OF THE NITROGEN WHEN ITS PRESSURE IS CHANGED TO 400 MM HG WHILE THE TEMPERATURE IS HELD CONSTANT.

Given:V1 = 14 L

P1 = 760 mm Hg

P2 = 400 mm Hg

V2 = ?

Equation:P1V1 = P2V2 

V2 = P1V1

P2

V2 = 760 mm Hg(14 L)

400 mm Hg 

V2 = 26.6 L

APPLICATIONS OF BOYLE’S LAW

Breathing Syringe

APPLICATIONS OF BOYLE’S LAW

Soda Can Scuba Diving

CHARLES’ LAW

Jacques CharlesV ά T

V1/T1 = V2/T2

Constant Variable:

P, n

A BALLOON HAS A VOLUME OF 2500 ML ON A DAY WHEN THE TEMPERATURE IS 30 0C. IF THE TEMPERATURE AT NIGHT FALLS TO 10 0C, WHAT WILL BE THE VOLUME OF THE BALLOON IF THE PRESSURE REMAINS CONSTANT?Given:T1 = 30 0C = 303 K

T2 = 10 0C = 283 K

V1 = 2500 ml

V2 = ?

Equation:V1 = V2

T1 = T2

 

V2 = V1T2

T1

V2 = (2500 ml)(283K)

303 K

V2 = 2, 335 mL

APPLICATIONS OF CHARLES’ LAW

COMBINED GAS LAW

= describes the relationship among the pressure, volume and

temperature at a constant amount of gas

= Boyle’s Law and Charles’ Law

COMBINED GAS LAW

Boyle’s LawP ά 1/V

P1V1 = P2V2

Charles’ LawV ά T

V1/T1 = V2/T2

V ά T/P

P1V1 = P2V2

T1 T2

Constant: n

A GIVEN MASS OF GAS HAS A VOLUME OF 800 ML AT -23 0C AND 300 TORR. WHAT WOULD BE THE VOLUME OF THE GAS AT 27 0C AND 600 TORR OF PRESSURE? THE AMOUNT OF GAS S CONSTANT.Given:V1 = 800 mLT1= -23 0C = 250 KP1 = 300 torrT2 = 27 0C = 300 KP2 = 600 torrV2 = ?

P1V1 = P2V2

T1 T2

 V2 = P1V1T2

P2T1 V2 =(300 torr)(800 mL)(300 K) (600 torr)(250 K) 

V2 = 480 mL

APPLICATIONS OF COMBINED GAS LAW

This law gives us an insight on how gases and volatile liquids should be stored.

Gas tanks containing LPG inside the container should be stored in cool places to prevent the build-up of a high pressure esp. if the gas is flammable.

GAY- LUSSAC’S LAWJoseph Louis Gay-

Lussac

P ά TP1/T1 = P2/T2

Constant: V, n

A 2 L FLASKS CONTAINS HELIUM GAS AT A PRESSURE OF 685 TORR AND A TEMPERATURE OF 0 0C. WHAT WOULD BE THE PRESSURE IN THE FLASK IF THE TEMPERATURE IS INCREASED TO 150 0C?Given:P1 = 685 torrT1 = 0 0C = 273 KT2 = 150 0C = 423 KP2 = ?Equation:

P1 = P2

T1 T2

 

P2 = P1T2

T1

P2 = (685 torr)(423 K) 273 K

P2 = 1, 061 torr

APPLICATIONS OF GAY-LUSSAC’S LAW

Pressure Cooker

AVOGADRO’S LAWAmedeo Avogadro

V ά nV1/n1 = V2/n2

Constant: P, T

IF 0.25 MOL OF ARGON GAS OCCUPIES A VOLUME OF 76.2 ML AT A PARTICULAR TEMPERATURE AND PRESSURE, WHAT VOLUME WOULD 0.43 MOL OF ARGON HAVE UNDER THE SAME CONDITIONS?Given:n1 = 0.25 mol

n2 = 0.43 mol

V1 = 76.2 mL

V2 = ?

Equation:

V1 = V2

n1 n2

V2 = V1n2

n1

V2 = (76.2 mL)(0.43 mol)

0.25 mol

V2 = 131 mL

APPLICATIONS OF AVOGADRO’S LAW

Inflating a balloon Breathing

IDEAL GAS LAWBoyle’s LawCharles’s LawAvogadro’s

LawGay – Lussac’s

Law

Ideal Gas Equation:

V ά nT/PPV = nRt

R (gas constant)

= 0.0821 L. atm mol. K

GAS CONSTANT

PV = nRT

R = PV nT

R = (1 atm) (22.4L)

(1 mol) (273K)

R = 22.4 atm.L 273 mol.K

R = 0.0821 L.atm/ mol.K

WHAT VOLUME WILL 1.27 MOL OF HELIUM GAS OCCUPY AT STP?

Given:n= 1.27 molP = 1 atmT = 273 KR = 0.0821 L.atm mol.KV = ?Equation:

PV = nRT 

V = nRT P

V =(1.27mol)(0.0821L.atm/mol.K)(273K) 1 atm

V = 28.5 L

APPLICATIONS OF IDEAL GAS LAW

Mountain climbers often carry oxygen tanks with them. The air at these higher altitudes is at lower atmospheric pressure or is ``thinner.'' This phenomenon in which pressure decreases with increasing altitude occurs in all fluids.

DALTON’S LAW OF PARTIAL PRESSURE

Partial Pressure- the pressure each gas would exert at the same temp. and at the same volume.

Ptotal = PA + PB + PC +……Pn

A CONTAINER HOLDS THREE GASES, OXGEN, CO2, AND HELIUM. THE PARTIAL PRESSURES OF THE THREE GASES ARE 2 ATM, 3 ATM AND 4 ATM RESPECTIVELY. WHAT IS THE TOTAL PRESSURE INSIDE THE CONTAINER?Given:

PA = 2 atm

PB = 3 atm

PC = 4 atm

Ptotal = ?

Equation:

Ptotal = PA + PB + PC

Ptotal = 2 atm + 3 atm+ 4 atm

Ptotal = 9 atm

IN A CLOSED SYSTEM, THE CHAMBER IS PRESSURIZED TO 1200 TORR. IF THE CHAMBER HOLDS 3 MOLES OF N2, 2 MOLES OF O2 AND 1 MOLE OF F2, WHAT IS THE PRESSURE OF EACH GAS?

P total = 3 P1+ 2P2 + 1P31200 torr = 6PP = 1200 torr/6 = 200 torr

N2 = 3 (2oo torr) = 600 torrO2 = 2 (200 torr) = 400 torrF2 = 1 (200 torr) = 200 torr 1200 torr

The mixing of gases due to molecular motion

The particles of gas spread out

-Passage of molecules of a gas from one container to another through a higher pressure;

- Particles of gas passing through a small opening

Diffusion Effusion

GRAHAM’S LAW OF EFFUSION

Thomas Graham- the rate of effusion

of gas is inversely proportional to the square root of its molar mass.

VB = √MWA

VA √MWB

HOW MUCH FASTER DOES O2 ESCAPE THROUGH A POROUS CONTAINER THAN SO2 UNDER SIMILAR CONDITION OF TEMPERATURE AND PRESSURE?

Given:

MW O2 = 32g/mol

MW SO2 = 64g/mol

√MWSO2 = V O2

√MW O2 = V SO2  

V O2 = √MWSO2

V SO2 = √MW O2

V1 = √64 g/mol

V2 √32 g/mol

 = 8/5.66 = 1.41 This means that O2 diffuses

1.41 times as fast as SO2

THE HEAVIER THE GAS IS, THE SLOWER THE GAS MOVES IN A GIVEN TEMPERATURE.

HCl = 36 g/mol NH3 = 17 g/mol

HCl NH3

NH3Cl

CONDENSED STATES OF

MATTER

Solids and Liquids- states in which the atoms or molecules are fairly close together and their behavior is determined (at least in part) by the attractions between them.

Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior

gas liquid solid

assumes the shape and volume of its container particles can move past

one another

assumes the shape of the part of the container which it occupies

particles can move/slide past one another

retains a fixed volume and shape

rigid - particles locked into place

compressible lots of free space between particles

not easily compressible little free space between

particles

not easily compressible little free space between

particles

flows easily particles can move past

one another

flows easily particles can move/slide

past one another

does not flow easily rigid - particles cannot

move/slide past one another

PROPERTIES OF LIQUID

EvaporationVapor PressureBoiling PointSurface TensionCapillary Action

TYPES OF SOLIDSVitreous or

Amorphous Solids- shapeless solids; solids

that do not have definite melting points; its particles do not have an orderly arrangement; their arrangement is random similar to liquids.

CRYSTALLINE SOLIDSsolids that

have definite melting point like NaCl and sugar; they have an orderly arrangement of particles.

ALLOTROPEScrystalline solids

that exist in various forms like carbon, it can exist as diamond and graphite.

   

Covalent Ionic Metall ic MolecularParticles that occupy the lattice sites

Atoms Positive and Negative ions

Metal atoms Molecules

Nature of bonding

Electron Sharing

Electrostatic attraction

Electrical attraction

between the outer level

electron and the nuclei

Van der Waals forces

Properties They are hard, nonvolatile, and

have high melting point. They are good

insulators.

They are quite hard and brittle.

They have fairly high

melting points and are good

insulators.

They have variable melting

points and hardness. They

are good conductors of

electricity.

They are generally soft and have low

melting points. They are good

insulators.

Examples Diamond, carborundum,

quartz

Sodium chloride,

potassium nitrate, sodium

sulfate

Copper, iron, aluminum

Ice, dry ice, sucrose, iodine

Propert ies of Solids Based on the Type of Bonding

Process Phase Change Direction of Movement of Heat

From ToMelting (fusion) Solid Liquid Heat goes into the solid as it

melts.Freezing(Solidification) Liquid Solid Heat leaves the liquid as it

freezes.Vaporization Liquid Gas Heat goes into the liquid as it

vaporizes.Condensation Gas Liquid Heat leaves the gas as it

condenses.Sublimation Solid Gas Heat goes into the solid as it

sublimes.Deposition Gas Solid Heat leaves the gas as it

solidifies.

PHASE CHANGES- occur by either the absorption or release of energy usually in the form of heat.

Heat Movement During Phase Change

HEATING CURVE OF WATER

PHASE DIAGRAM OF WATER

THANK YOU VERY

MUCH!!!Prepared by:

Divina Michelle B. Belcina