Ideal Gases

Question 1

One mole definition

Answer 1

the amount of substance that contains as mamy elementary entities as there are atoms in 0.012kg of carbon-12

Question 2

what does 1 mol of any substance contain

Answer 2

6.02 * 10^23 individual atoms or molecules

Question 3

total number of atoms in a substance equation

Answer 3

N (total no. of molecules) = n (number of moles) x avagadro’s constant

Question 4

How do atoms in an ideal gas cause pressure?

Answer 4

The atoms or molecules in a gas are always moving and when they collide with the walls of the container , the container exerts a force on them (Newton’s 3rd Law), changing their momentum as they bounce off the wall.

Question 5

What happens to the velocity of the atom when it bounces off the container?

Answer 5

It becomes negative since velocity is a vector

Question 6

pressure and volume relationship

Answer 6

if the temperature and mass of gas remain constant then the pressure of an ideal gas is inversely proportional to its volume.

Question 7

what is boyle’s law

Answer 7

pressure exerted by a gas at constant temperature varies inversely with the volume of the gas.

Question 8

Pressure and temperature relationship

Answer 8

if the volume and mass of a gas remains constant, the pressure of an ideal gas is driectly proportional to its absolute (thermodynamic) temperature in kelvins

Question 9

what is the combined gas law

Answer 9

P1V1/T1 = P2V2/T2

Question 10

what is the combined gas law constant, nR

Answer 10

pV/t

Question 11

what is the value for the molar gas constant

Answer 11

8.31 JK -1 mol -1

Question 12

what is the equation of state of an ideal gas

Answer 12

pV/T = nR OR pV = nRT

Question 13

how is the Boltzmann constant calculated

Answer 13

the molar gas constant/ avagadro’s constant

Question 14

what is the boltzmann constant

Answer 14

1.38 x 10^-23

Question 15

equation of state of an ideal gas with the boltzmann constant

Answer 15

pV = N(number of particles in gas sample)k(avagadro’s constant)T

Question 16

what affects particles having different speeds

Answer 16

particles have different masses so their r.m.s. speeds will be different

Question 17

what is the internal energy of a gas

Answer 17

the sum of the kinetic and potential energies

Question 18

what is the nature of internal energy in an ideal gas

Answer 18

one of the assumptions of an ideal gas is that the electrostatic forces between particles is negligible except during collisions, so there is no electric potential energy in an ideal gas. all the internal energy is in the form of the KE of particles.

Question 19

Why does higher temperature lead to higher pressure

Answer 19

The hotter the gas, the faster the molecules move
Hence the molecules collide with the surface of the walls more frequently
Since force is the rate of change of momentum:
Each collision applies a force across the surface area of the walls
The faster the molecules hit the walls, the greater the force on them
Since pressure is the force per unit area
Higher temperature leads to higher pressure

Question 20

pressure in an ideal gas

Answer 20

The frequency of collisions of the gas molecules per unit area of a container

Question 21

what does isothermic mean

Answer 21

if a change in a gas is isothermic it means temperature is constant

Question 22

what does isobaric mean

Answer 22

when change has no change in pressure