Gas Laws

Question 1

Gas

Answer 1

a substance that has no well defines boundary but diffuses rapidly to fill the container in which it is placed

Question 2

boyles law

Answer 2

at constant temperature the volume of a fixed mass of gas is inversely proportionate to its pressure

Question 3

charles’ law

Answer 3

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

Question 4

Gay lussacs law of combining volumes

Answer 4

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

Question 5

avogadros law

Answer 5

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

Question 6

ideal gas

Answer 6

a gas that perfectly obeys all of the assumptions of the kinetic gas theory under all conditions of temperature and pressure

Question 7

real gas

Answer 7

different from an ideal gas because forces of attraction and repulsion do exist between molecules and the volume of the molecules is not always negligible

Question 8

How do you convert from °C to Kelvin?

Answer 8

Add 273 to the amount of °C

Question 9

How to convert from cm^3 to m^3

Answer 9

Add x10^-6 to the end

Question 10

How to convert from cm^3 to Litres

Answer 10

Cm^3 divide by 1000

Question 11

How to convert from litres to m^3

Answer 11

Litres divided by 1000

Question 12

How to convert from kPa to Pa

Answer 12

Multiply by 1000

Question 13

What are the conditions of S.T.P

Answer 13

Temp- 273 K
Pressure- 100kPa
Molar volume- 22.4L

Question 14

What are the conditions of R.T.P

Answer 14

Temp- 298K
Pressure- 100kPa
Molar volume-24L

Question 15

What does STP stand for

Answer 15

Standard temperature and pressure

Question 16

What does RTP stand for

Answer 16

Room temperature and pressure

Question 17

Explain boyles law

Answer 17

1. Expanding the container increases volume and decreases the pressure
2. Making the container smaller decreases the volume and increases the pressure

Question 18

What gases follow boyles law

Answer 18

For all gases

Question 19

What unit does temperature have to be in for Charles’ law to be true?

Answer 19

When temperature is in KELVIN

Question 20

What is the combined gas law formula?

Answer 20

(P1)(V1)/(T1)=(P2)(V2)/(T2)

Question 21

What are the important things to remember when using the combined gas law formula

Answer 21

Gas 1+2 have to all have the same unit
Temperature HAS to be in KELVIN

Question 22

How do you find the volume of a gas?

Answer 22

Moles x molar volume
(Molar volume is either stp or rtp)
Volume must be in L

Question 23

Give 2 assumptions of the kinetic gas theory

Answer 23

1. No attractive or repulsive forces between molecules/point particles of the gas
2. Gas molecules are so small and so far apart that the actual volume of the point particles is negligible compared to the space that they occupy
3. The average Kinetic energy of the molecules in a gas is directly proportional to the temperature

Question 24

Limitations of the kinetic gas theory

Answer 24

1. All real gases do experience tiny attractive/repulsive forces between molecules. Some molecules have permanent dipoles and form dipole dipole or hydrogen bonding forces. Or if it is non polar it will form van dear waals
2. It is not true that the volume is negligible compared to the space particles occupy. Under high pressure when molecules are forced close together, their volumes are not negligible compared to the space they occupy

Question 25

Under what conditions do real gases behave like ideal gases

Answer 25

At low pressure when the molecules are spaced far apart
At high temperature when the molecules are moving rapidly, thus minimising intermolecular forces

Question 26

What is the ideal gas law equation

Answer 26

pV= nRT

Question 27

What do you use the ideal gas law for

Answer 27

To find the volume of a gas when we are not given at stp or rtp in a question

Question 28

What units must all the parts of the ideal gas law be in

Answer 28

P= Pa NOT kPa
V= m^3
R= 8.314 ( on exam cover)
n=moles
T= Kelvin
You have to convert to these most of the time

Question 29

Why does the temperature have the be in Kelvin for Charles law?

Answer 29

If you plot line on the Celsius scale line will not pass through the origin meaning the volume of gas would not be directly proportional to the temperature

Question 30

diffusion

Answer 30

the random spreading out of molecules from an area of high concentration to areas of low concentration to fill a container