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Flashcards in Gas Laws and the Mole Deck (63)
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1

mole

The amount of a substance which contains 6.023 x 10²³ particles of that substance
(Avogadro's number or constant = L)

2

kelvin

Celsius + 273

3

standard temp

273 K

4

normal temp

293 K

5

standard pressure

1 x 10⁵ Pa / 100,000 Pa
(100 kPa)

6

litre and cm³

1 litre = 1000 cm³

7

Boyle's Law

States that: at constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure

8

Charles' Law

States that: at constant pressure, the volume of a fixed mass of a gas is directly proportional to its temperature measured on the Kelvin scale

V ∝ T

9

General Gas Law

hback

10

Gay Lussac's Law of combining volumes

the volume of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers provided the volumes are measured at the same temp + pressure

11

Avogadro's Law

state that: equal volumes of gases contain equal numbers of molecules under the same conditions of temp + pressure

12

Molar Volume

at standard temp + pressure (s.t.p) one mole of any gas occupies 22.4 litres/dm³

at r.t.p: 24 litres/dm³

13

s.t.p

standard temperature + pressure

14

r.t.p

room temperature + pressure

15

Ideal Gas

one which perfectly obeys all the gas laws + all the assumptions of the kinetic theory of gases under all conditions of temperature + pressure

16

Gas

a substance that has no well defined boundaries but diffuses rapidly to fill any container in which it was placed

17

Pressure

The pressure of a gas is the force that the gas exerts on each unit area (eg. one square meter) of its container

18

Si unit of pressure

Newton per meter squared (N'm²)

Also called the pascal (Pa)

19

Normal atmospheric pressure

1 x 10⁵ N/m²

1 x 10⁵ Pa

20

Kilopascal

as numbers can be large, the kilo-pascal is also used

21

Volume

how much space something takes up

22

Si unit of volume

cubic meter (m³)

23

Gas & containers

volume of a sample of gas is same as container it is held in

24

Other ways volume is measured

cm³
litre (also known as dm³)

25

Pressure & volume

As pressure goes up, volume goes down

26

Pressure & temperature

as temperature (K) goes up, so does the pressure

27

Pressure & temperature limitation

only works when temp is on Kelvin scale

28

The Kinetic Theory of Gases - assumptions

1. Gases made up of particles that are in continuous rapid, random motion, colliding w/ each other + walls of container

2. No attractive or repulsive forces between particles of a gas

3. Gas particles are so small + widely separated that total volume of all particles is negligible compared with space they occupy

4. Collisions between particles are perfectly elastic, ie no overall loss of kinetic energy in these conditions

5. Average kinetic energy of particles in a sample of a gas is proportional to temp measured on Kelvin scale

29

The Kinetic Theory of Gases - limitations

2. contrary to assumption 2, there are forces of attraction between particles of a gas
eg. Van der Waals forces / Diople-dipole forces

3. contrary to assumption 3, it is not valid to say that total volume of gas is always negligible compared with the space that they occupy

-since these assumptions are not simply true, kinetic theory gases can only apply perfectly to what might be termed an ideal gas - no such gas exists

30

gases deviate most from ideal behaviour when:

-under high pressure (particles forced close together
-at low temperature (particles moving slowly)
-under these conditions, effect of inter-molecular fores becomes significant = volume of particles cannot be ignored when compared to volume in which they move