Gas Laws

Front 1

(Ideal-er) gases have low _______ and high ______

Back 1

ideal-er gases have low pressure and high temperature

liquids have higher pressure and lower temperature

Front 2

Ideal gas particles move in straight lines because they do not...

Back 2

ideal gas particles move in straight lines because they do not attract nor repel each other

Front 3

Temperature must always be in ___ , which is degrees C + ___

Back 3

Kelvin, C +273

Front 4

What must be constant with the combined gas law?

Back 4

Mass must be constant with the combined gas law.

Front 5

Ideal gases obey the gas laws over which temperatures and pressures?

Back 5

Ideal gases obey the gas laws over all temperatures and pressures.

Front 6

What is STP?

Back 6

273K and 1 atm is Standard Temperature and Pressure. 1 mole of all ideal gases @ STP occupies 22.4 L

Front 7

All ideal gases @ STP have the same ___ whereas their ___ vary depending on the gas.

Back 7

All ideal gases @ STP have the same volume (22.4L) whereas their molecular masses vary depending on the gas.

Front 8

What is Avogadro's Principle?

Back 8

At a constant temperature and pressure, equal volumes of gases contain equal numbers of moles, a stoichiometric equivalency. The volume of a gas is directly proportional to the number of moles.

Front 9

At a constant temperature and pressure, gases react in simple whole number ratios of their ___ or ___

Back 9

At a constant temperature and pressure, gases react in simple whole number ratios of their volumes or moles. Also known as the Law of Combining Values.

Front 10

Which equation is most useful for finding the density of a known gas?

Back 10

D = PM/RT

Front 11

Dalton's Law of Partial Pressures is defined as...?

Back 11

Dalton's Law of Partial Pressures is defined as

the total pressure of a mixture of non-reacting gases is the sum of their individual pressures. Each gas contributes to the total pressure in proportion to the fraction, by volume, in which it is present.

Front 12

When collecting gas over water, Ptotal = ?

Back 12

When collecting gas over water,

Ptotal = Pwater + Pgas. The gas must be non-polar or else it will dissolve.

Front 13

The number of moles in a sample is proportional to the p_____?

Back 13

The number of moles in a sample is proportional to the partial pressure. Related through the mole fraction where Xa = Pa/Ptotal.

Front 14

The rate of effusion of a gas is proportional to the reciprocal of...?

Back 14

The rate of effusion of a gas is proportional to the reciprocal of the square root of density.

Front 15

What is effusion?

Back 15

Effusion is the moving of gas molecules from a region of higher pressure to a region of lower pressure through a very small opening.

Front 16

Density is directly proportional to...?

Back 16

Density is directly proportional to molar mass.

Front 17

rA/rB = the square root of ...?

Back 17

rA/rB = the square root of dB/dA. (inversely proportional according to Graham's Law of Effusion)

Front 18

Different particles will have different ... because their ... is different. Think kinetic Theory.

Back 18

Different particles will have different velocities because their mass is different.

Front 19

The ___ the mass, the ___ the velocity.

Back 19

The bigger the mass, the slower the velocity.

Front 20

Wet gas has as much ___ as it can hold at ___ ?

Back 20

Wet gas has as much water vapour as it can hold at the temperature of the water.

Front 21

Vapor pressure says that water vapor present in...

Back 21

Vapor pressure says that water vapor present in a mixture of gases has a partial pressure like any other gas, that depends solely on the temperature.

Front 22

When we collect a ___ gas, we usually want to know how much ___ this corresponds to.

Back 22

When we collect a wet gas, we usually want to know how much dry gas this corresponds to.

Front 23

The volume of a given amount of gas, held a constant temperature, _______ _______ with the applied pressure.

Back 23

The volume of a given amount of gas, held a constant temperature, varies inversely with the applied pressure. The greater the volume, the less the particles collide with the walls, thus there is less pressure exerted on the walls.

Front 24

The ___ the temperature and the ___ the temperature, the more ideal a gas is.

Back 24

The greater the temperate and the lower the pressure, the more ideal a gas is.

Front 25

When P is kept constant, a greater average kinetic energy means the volume ___?

Back 25

When P is kept constant, a greater average kinetic energy means the volume expands. Volume is directly proportional to temperature.

Front 26

What happens to molecules of a gas at absolute zero?

Back 26

At absolute zero, molecules stop moving completely.

Front 27

A mole fraction is, for any component in a mixture, the ratio of what?

Back 27

A mole fraction is the ratio of the number of a component's moles to the total number of moles from all components.

Front 28

A mole fraction, Xa, is equal to what?

Back 28

The partial pressure of component, Pa / Ptotal

Front 29

A gas sample has a huge # of particles moving randomly, colliding constantly, changing velocities and so experiencing...?

Back 29

A gas sample has a huge # of particles moving randomly, colliding constantly, changing velocities and so experiencing changes in their kinetic energies.

Front 30

What is gas pressure?

Back 30

The net effect of innumerable collision made by gas particles on the walls.

Front 31

When there are no attractive forces or repulsive forces between gas atoms, what is their trajectory?

Back 31

Molecules travel in straight lines when no attractions or repulsions, where their individual pressures are not influenced by near misses or collisions.

Front 32

PV/T is constant for what type of gases?

Back 32

Ideal gases.

Front 33

Why do real gases fit the ideal gas laws so well @ ordinary pressures?

Back 33

Real gases fit the ideal gas laws so well @ ordinary pressures because the volume taken up by the molecules themselves is a very tiny fraction of the container's volume when at ordinary pressures (less molecules).

Front 34

The more molecules, the ___ the pressure, the ___ the fraction of space taken up by the molecules.

Back 34

The more molecules, the greater the pressure, the greater the fraction of space taken up by the molecules.

Front 35

Why do real gases deviate more and more from ideal behaviour @ higher pressure?

Back 35

Real gases deviate more and more from ideal behaviour @ higher pressures because the fraction of space taken up by the molecules themselves is greater. This lost space is not accounted for in the ideal gas laws.

Front 36

What two factors influence the deviation of real gases from ideal gas behaviours? In which cases does each one show up?

Back 36

1. Real gas molecules do have an individual volume. Affects high-pressures because the space taken up by the molecules is greater at higher pressures.

2. Real gas molecules attract each other (IMF).

Affects low pressures.

Front 37

How do IMF affect the pressure of a gas?

Back 37

Greater IMF mean the particles cling together and so strike the walls less often and with less force and therefore decrease the pressure.

Front 38

___ atoms and ___ intermolecular forces mean a more ideal gas.

Back 38

Smaller atoms and less intermolecular forces mean a more ideal gas.

Front 39

The ___ from a liquid, the more ideal a gas is.

Back 39

The further from a liquid (low temperature + high pressure), the more ideal a gas is.