1.1

Question 1

what are the important physical properties of gases?

Answer 1

highly compressible

thermally expandable

low viscosity (the resistance to being poured)

most have low densities (means have low mass)

infinitely miscible (to be able to mix)

diffuse rapidly (move prapidly from place to another)

uniformly occupy full volme of container (even distribution)

exert pressure on all surfaces in contact with

gases take the shape and volume of the container that they are in

Question 2

What is the ideal gas model?

Answer 2

predict and explain observation in gas sample

Question 3

When does the ideal gas model apply?

Answer 3

Applies at low pressure and high (room) temperature

non scientific image: think of a deflated balloon on an element

Question 4

What does the ideal gas model postulate?

Answer 4

• articles in constant random motion; moves in a straight line unitl it crashes into something
• volume (size) of particle is negligible; because volume is mostly empty space
• particles exert no force (attraction/repulsion) on each other

Question 5

what does the kinetic moelcular theory state?

Answer 5

ALL PARTICLES ARE IN A CONSTANT RANDOM MOTION

Question 6

What does the kinetic molecular theory postulate?

Answer 6

• gases: particles act independently
• higher temperature = higher average kinetic energy

Question 7

Describe the motion of particles of the three states of matter (gas, solid, liquid)

Answer 7

SOLID: paritcles vibrate in a fixed position

LIQUID: particles move away from neighbours; has a surface area; limited to its own volume

GAS: random movement of particles occupies the whole volume of container

Question 8

Define temperature

Answer 8

the measure of the average kinetic energy of particles in sample

Question 9

At a given temperature, all gases have the same:

Answer 9

• molecular kinetic energy DISTRIBUTIONS
• average molecular kinetic energy

Question 10

What is the purpose of the kinetic molecular thoery?

Answer 10

kinteic model of gases provides explanation of experimental observation of gas behaviour

Question 11

What are the characterstics of gases explained by the kinetic molecular theory?

Answer 11

• relative densities
• variation of gas pressure with temperature
• rate of evaporation with temperature
• diffusion

Question 12

What does the ideal gas model explain?

Answer 12

• explains changes in P and T on molecular level
• POSTULATE: particles in constant random motion
• POSTULATE: volume of individual particles assumed to be negligible
• PSTULATE: particles assumed to exert no force on each other
• APPLIES ONLY WHEN:shows behaviour that real gases approach at low pressure and high (room teperature)

Question 13

Define Effusion

Answer 13

the escape of molecules through a small hole into an empty container (vacuum)

Question 14

Define diffusion

Answer 14

the gradual mixing of molecules of different gases

Question 15

Units of amount in moles (n)

Answer 15

moles (mol)

Question 16

volume (V)

Answer 16

m^3 ( 1000L)

Question 17

pressure (P)

Answer 17

Pascals (Pa)

Question 18

temperature (T)

Answer 18

Kelvin (K)

Question 19

true or false are V,P,T and n all interdependent (which means that a change in one can affect all other variables)

Answer 19

true

Question 20

True or false is the distribution of moelcular speeds related to temperature and molar mass?

Answer 20

true