Change of State and Ideal Gas Molecules

Question 1

What is the arrangement and motion of particles in a solid?

Answer 1

• Regular, tightly packed arrangement
• Particles only vibrate around a fixed position

Question 2

What is the arrangement and motion of particles in a liquid?

Answer 2

• Less regular and closely packed arrangement than solid, with the particles being reasonably close together (particles are still touching each other)
• Particles can flow as they can move past each other, therefore there is no definite shape

Question 3

What is the arrangement and motion of particles in a gas?

Answer 3

• Random arrangement, spread far apart
• Particles move randomly and quickly in all directions

Question 4

What always happens when a system is heated and what two things can occur as a result of this?

Answer 4

• The kinetic energy of the particles within the system increase, leading to increased movement speed and a larger distance between them
• This can increase the temperature of the system
• It can alternatively contribute to a change in state within the system

Question 5

When heating ice, why does the temperature remain constant upon reaching 0 degrees until a change in state is observed?

Answer 5

The energy being added to the system is being used to break the bonds of the substance instead of increasing the temperature of the system

The same applies for the conversion of liquid into gas etc.

Question 6

What is specific heat capacity defined as?

Answer 6

The amount of energy required to heat 1kg of the given substance by 1 degrees celcius

Question 7

What is the relationship between change in energy, mass, specific heat capacity and change in temperature

Answer 7

• ΔQ = m x c x ΔT
• Change in energy = Mass x Specific Heat Capacity x Change in Temperature

Question 8

Why do gas molecules have pressure within a container?

Answer 8

• The gas molecules move randomly and quickly, and will collide with the wall of the container exerting a force onto it
• Pressure = Force/Area, so a force in the container means pressure in the container

Question 9

What is absolute zero, what is it in Kelvin and celcius and how do you convert between the two units?

Answer 9

• Absolute zero is the temperature that particles have no energy, so will have no motion
• It is zero kelvin, and -273 celcius
• Therefore kelvin = celcius + 273

Question 10

What is the description and explanation for the relationship between pressure and volume at a constant temperature for a contained gas?

Answer 10

• Pressure is inversely proportional to volume, so is directly proportional to 1/volume
• This is because increasing volume spreads the particles apart so reduces the density of the particles (ρ=m/v) which means there are fewer collisions with the walls of the container per second
• This leads to a reduction in the exerted force on the walls of the container per second, therefore, since P = F/A, pressure decreases

Question 11

What is the description and explanation for the relationship between pressure and temperature in Kelvin at a constant volume for a contained gas?

Answer 11

• Temperature in Kelvin and pressure and directly proportional
• This is because increasing the average temperature increases the average kinetic energy of the particles, which increases their average speed, which increases the number of collisions per second with the walls of the container as well as making these collisions more forceful
• This means more force is exerted onto the container per second, and since P = F/A, a higher pressure

The temperature must be in Kelvin, otherwise it will not be directly proportional

Question 12

What is the relationship between initial pressure and initial temperature, and final pressure and final temperature

Answer 12

P₁/T₁ = P₂/T₂

• This is all in the same system
• You must ensure the temperature is in Kelvin, otherwise it won’t work

Question 13

What is the relationship between initial pressure and initial volume, and final pressure and final volume

Answer 13

P₁ x V₁ = P₂ x V₂