Gas Laws

FundmentalsFundmentals

KINETIC MOLECULAR THEORY KINETIC MOLECULAR THEORY

KMT is a model to explain the behavior of gaseous particles and is based on extensive observations

If a gas follows all the ideas of the KMT, it is said to be an ideal gas

THE KINETIC THEORYTHE KINETIC THEORY

1. All matter is composed of very small particles

2. These particles are in constant motion

3. Collisions between particles are perfectly elastic

PRESSUREPRESSURE

Pressure is defined as force per unit area

Units: kPa, atm, mmHg, torr

VOLUMEVOLUME

Volume is defined as the amount of space an object occupies

Units: cm3, mL, L

DALTON’S LAW DALTON’S LAW

Dalton’s LawDalton’s Law

The physical properties of gases are affected by temperature and pressure

John Dalton found that each gas in a mixture exerts pressure independently of the other gases present

Dalton’s LawDalton’s Law

The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases

Ptotal = P1 + P2 + ...When a H2 gas is collected by water displacement, the gas in the collection bottle is actually a mixture of H2 and water vapor

GIVEN:

Pgas A = 13.7 KPa

Pgas B = 5.3 KPa

Pgas C = 4.5 KPa

Ptotal = PA + PB + PC

WORK:

Ptotal = PA + PB + PC

Ptotal =

Ptotal =

What is the total pressure in a container if gas A has a pressure of 13.7 KPa, gas B has a pressure of 5.3 KPa and gas C exerts a pressure of 4.5 KPa?

Ex. Problem 1: Dalton’s LawEx. Problem 1: Dalton’s Law

The total pressure in the container is Ptotal

GIVEN:

PO2 = ?

PCO2 = .7 atm

PN2 = .12 atm

Ptotal = .97 atm

WORK:

Ptotal = PO2 + PCO2 + PN2

Ex. Problem 2: Dalton’s LawEx. Problem 2: Dalton’s Law

A mixture of O2, CO2, and N2 has a total pressure of .97 atm. What is the partial pressure of O2, if the partial pressure of CO2 is .70 atm and the partial pressure of N2 is .12 atm.The total pressure is given, you need to find Poxygen.

BOYLE’S LAW BOYLE’S LAW

Irish chemist (1627-1691)

Performed the first quantitative experiments on gases

Used j-shaped tube to study the relationship between pressure of trapped gas and its volume

Boyle’s LawBoyle’s Law

Boyle’s LawBoyle’s Law Boyle’s Law states that at constant

temperature the volume of a fixed amount of gas is inversely related to pressure • When the volume INCREASES, pressure

DECREASES• When the volume DECREASES, pressure

INCREASES

Boyle’s Law:

P1V1 = P2V2

Initial conditions

Final conditions

GIVEN:

V1 =

P1 =

V2 =

P2 =

WORK:

P1V1 = P2V2

Ex. Problem #1: Boyle’s LawEx. Problem #1: Boyle’s Law

The volume of a gas is 200 mL at a pressure of 100 KPa. What is its volume at a pressure of 200 KPa?

P1V1 = P2V2

GIVEN:

V1 =

P1 =

V2 =

P2 =

WORK:

P1V1 = P2V2

Ex. Problem #2: Boyle’s LawEx. Problem #2: Boyle’s Law

If the pressure of the gas in the 4.0 L volume is 200 KPa what will the pressure be at 2.5 L?