Properties of gases - Ch10

Question 1

Diffusion

Answer 1

Spreading out of particles from an area of high concentration to an area of low concentration.

Question 2

Temperature

Answer 2

C° (+273) –> K
Use: thermometre

Question 3

Pressure

Answer 3

KPa (x1000) –> Pa
Use: Barometer

Question 4

Volume

Answer 4

m³ (x10⁻⁶) –> cm³

Question 5

Boyle’s law

Answer 5

At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

Question 6

Charle’s law

Answer 6

At constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature measured on Kelvin Scale.

Question 7

Combined gas law (Boyle’s + Charles’)

Answer 7

P1V1 / T1 = P2V2 / T2

Question 8

Gay-Lussac

Answer 8

Gases react in the ratio of small whole numbers at constant temperature and pressure.

Question 9

Avogadro’s law

Answer 9

Equal volumes of gases contain equal numbers of molecules under the same conditions of temperature and pressure.

Question 10

Molar volume

Answer 10

• STP = 22.4 L
• Room temp = 24 L

Question 11

Volatile

Answer 11

Low boiling point

Question 12

Experiment

Answer 12

1. Measure mass of flask with Al foil + rubber band
2. Leave 8 minutes in boiling water bath + hot plate + pinhole in foil (to equalise pressure) until fully vaporises
3. Take out, let it cool, dry + reweigh + substruct from initial volume.

Question 13

PV=nRT

Answer 13

• P = Pa (barometer)
• V = m³
• n = ? (mass)
• R = 8.31 (always given)
• T = K (thermometer)

Question 14

Brownian motion

Answer 14

Random movement of tiny particles in a liquid or a gas.

Question 15

Kinetic theory of gases assumptions:

Answer 15

• All collisions are perfectly elastic
• There are no attractive or repulsive forces between molecules of a gas
• Their volume is negligible compared to the space they occupy

Question 16

Kinetic theory of gases limitations:

Answer 16

• There are attractive and repulsive forces between molecules of a gas
• Their volume is not negligible under high pressure

Question 17

Ideal gas:

Answer 17

One that follows all the assumptions on the kinetic theory of gases.

Question 18

Gas closest to ideal

Answer 18

H2 (Hydrogen GAS)

Question 19

Closest noble gas

Answer 19

He (Helium), because it is the smallest noble gas

Question 20

Real gas

Answer 20

Differs from ideal gases because:
- Forces of attraction + repulsion do exist between the molecules
- Volume of the molecules is not negligible

Question 21

When are real gases closest to be ideal?

Answer 21

High temperature, low pressure.