Gas Behavior I & II - Ideal Gas Law, Kinetic Molecular Theory

) define pressure as force per unit area, and recognize various units of pressure (e.g. atm, bar, kPa) 7) perform calculations with the ideal gas law (PV = nRT) to relate the pressure, volume, temperature and amount of a gas 8) perform calculations that relate density and molar mass of gases (ρ = MMቀ P RTቁ) 9) describe the molecular basis for pressure and temperature of a gas in terms of the force and frequency collisions of gas particles 10) rationalize all behavior predicted by the ideal gas law in terms of the kinetic molecular theory of gases and particle collisions

Ideal Gas Law Equation

PV=nRT

What are the variables in the Ideal Gas Law?

P= Pressure

V= volume

n= number of particles

R= Ideal Gas Law constant

T= temperature

Gas particle distance

Far apart

Gas particle interaction

minimal, little to no interaction

for equal number of gas particles at same volume and temperatue, heavier gas molecules produce ___ pressure as lighter molecules

same

the relation between gas pressure and mass of gas particles

does not vary

the relation between gas pressure to volume of gas

inversely proportional

the relation between gas pressure and temperature of gas

directly proportional

when temperature is measured in Kelvin, the intercept of a P vs T graph is ____

effectively zero

when temperature is measured in Celsius, the intercept of a P vs T graph is ___

far from zero

the relation between gas pressure and number of gas particles

directly proportional

Describe proportionality of behavior of pressure of gas

P does not vary with gas mass, P ∝ 1/V, P ∝ T, P ∝ n

Describe proportionality relationship of gas variables

P ∝ nT/V

statement describing relationship between variables and graph of P vs T, P vs n and P vs V

P = 0 when V = ∞, or n = 0, or T = 0 (in K)

converting value from Celsius to Kelvin

+273.15

A 50.0 L compressed gas cylinder holds 3.00×104 kPa of

N2 gas at 25°C. How many moles of gas are in the cylinder?

605 moles

A balloon has a volume of 0.500 L at 25°C and 1.00

bar pressure. What is the new volume if T is increased

to 50°C and P to 2.00 bar ?

0.271 L

A unknown gas has a density of 1.38 g/L at 17°C

and 1.04 bar. What is the molar mass?

32.0 g/mol

According to the Ideal Gas Law, if temperature of gas increases, the pressure will ____

increase

As temperature of gas increases, average speed and kinetic energy of particles ____

increases

On average, gas particles in same size chamber at higher temperature take more or less time to cross the chamber

less

To cross the chamber, gas particles at higher temperature collide with chamber surface less or more often

more often

heated gas particles

increase in speed, kinetic energy, frequency and force of collisions

According to the Ideal Gas Law, if number of gas particles increases, the pressure will ___

increase

increase number of gas particles, same temperature, average speed ____

stays same

increase number of gas particles, same temperature, kinetic energy ____

stays same

increase number of gas particles, same temperature, collision frequency ____

occurs more often

Relationship between overall gas pressure and particle mass

does not vary

Relationship between particle mass on speed and kinetic energy

heavier particles have lower speed, same kinetic energy as lighter particles

Relationship between particle mass on collision force and frequency

greater force, lower frequency

temperature

measurement of average kinetic energy of particles

pressure

measurement of frequency and force of particle collisions

n↑ = P↑

more particles = greater collision frequency

T↑ = P↑

greater kinetic energy of particles results in

greater force and frequency of collisions

V↑ = P↓

more space means particles at the same

speed strike the container walls less often,

decreasing collision frequency

T↑ = V↑

greater kinetic energy increases pressure,

pressure in > pressure out, outward force

expands the container until collision

frequency drops so pressures are equal

P↑ = V↓

pressure out > in causes inward force that

compresses the container, until collision

frequency increases so pressures are equal