Properties of gases

Question 1

What is a gas

Answer 1

A gas is a substance that has no well define boundaries but diffuses rapidly to fill any container in which it is placed in

Question 2

What is standard pressure

Answer 2

1x10^5 Pa or 100kPa

Question 3

What is standard temperature

Answer 3

273 Kelvin

Question 4

State Boyle’s Law

Answer 4

Boyle’s Law states that at constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure. pV = k

Question 5

State Charle’s Law

Answer 5

Charle’s Law states that, at constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature measured on the Kelvin Scale. V/T = k

Question 6

What is 1 mole of any gas at STP

Answer 6

22,400cm^3/22.4L

Question 7

What is 1 mole of any gas at room temperature and pressure

Answer 7

24L

Question 8

What is an ideal gas

Answer 8

An ideal gas is one that perfect obeys all the assumptions of the kinetic theory under all conditions of temperature and pressure

Question 9

What is a real gas

Answer 9

Real gases differ from ideal gases because: 1. Forces of attraction and repulsion do exist between the molecules and 2. The volume of the molecules is not negligible

Question 10

State Avogrado’s Law

Answer 10

equal volumes of gases contain equal number of molecules under the same conditions of temperature and pressure

Question 11

State gay-Lussac’s Law of combining volumes

Answer 11

In a reaction between gases, the volume of the reacting gases and the volumes of any gaseous products are in he ratio of small whole numbers provided the volumes are measured at the same temperature and pressure

Question 12

Name any 2 assumptions of the kinetic theory of gases

Answer 12

1. gases are made of molecules that are in continuous rapid, random motion, colliding with each other and with the walls of the container.
2. There are no attractive or repulsive forces between the molecules of a gas, i.e te molecules are independent of each other (*limit)
3. The gas molecules are so small and so widely separated that the actual volume of the molecules is negligible compared with the space they occupy (*limit)
4. When the molecules collide, the collisions are perfectly elastic, i.e there is no loss of kinetic energy in these collisions although there may be a transfer of energy between the colliding particles

Question 13

State the main points about temperature.

Answer 13

It is a measure of the degree pf hotness of an object.
There are two scales: Celsius Scale and Kelvin/Absolute Scale.
0° C= 273 K
-273° = 0 K
100°C = 373 K

Question 14

What is the boiling point and freezing point of water.

Answer 14

Boiling point: 100°C

Freezing point: 0°C

Question 15

What is 1 cubic metre in cm^3.

Answer 15

1000000 cm^3

Question 16

What is a volatile liquid and give an example.

Answer 16

A liquid with a low boiling point. eg propanone/acetone