P3 - Particle Model Of Matter

Question 1

What is density?

Answer 1

Density is the mass per unit volume

Question 2

What is the equation that links density, mass and volume?

Answer 2

P = M/V

p = density (kg/m^3)
m = mass (kg)
v = volume (m^3)

Question 3

RP5: Describe a method to determine the density of a regular solid object

Question 4

RP5: Describe a method to determine the density of an irregular solid object or liquid

Question 5

Why do objects float?

Answer 5

If the object is less dense than water it floats
If the object is denser than water it sinks

Question 6

Explain how doing work on an enclosed gas such as a bicycle pump leads to an increase in temperature of the gas

Answer 6

Gas applies pressure to the plunger of the pump , which exerts a force on the plunger

Work has to be done against this force to push down the plunger

This transfers energy to the kinetic energy stores of the gas particles, increasing the temperature

If the pump is connected to a tyre, you should feel it getting warmer

Question 7

Explain why it is easy to compress a gas, but not solids or liquids

Answer 7

The atoms in gases are more spread out than liquids and solids

Question 8

Describe the motion of molecules within a gas

Answer 8

Constant random motion
Random directions (erratic)
Random speeds

Question 9

Compare solids, liquids and gases

Question 10

Why is mass conserved when a substance changes state?

Question 11

What type of change are changes of state? How does this differ from chemical changes?

Answer 11

Physical changes

Different from chemical changes because the material recovers its original properties if the change is reversed

Question 12

What is internal energy?

Answer 12

Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system

Question 13

How does heating change the energy stored within a system?

Answer 13

Increases the energy of the particles in the system, which increases the overall temperature of the system or produces a change of state

Question 14

During a change of state, what happens to the temperature?

Answer 14

The temperature remains constant. The supplied energy is not used to increase the kinetic energy, but to break the intermolecular forces

Question 15

If the temperature of the system increases, the increase in temperature depends on what?

Answer 15

Mass of the substance
Type of material
Energy input to the system

Question 16

What is specific heat capacity?

Answer 16

The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.

Question 17

What is the equation that links change in thermal energy, mass, specific heat capacity and temperature change?

Answer 17

∆E = m c ∆θ

∆E = J

mass = kg

specific heat capacity = J/kg °C

∆θ =°C.

Question 18

What is specific latent heat?

Answer 18

The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature.

Question 19

What is the equation that links energy for a change of state, mass and specific latent heat?

Answer 19

E = mL

energy = J
mass = kg
specific latent heat = J/kg

Question 20

What is the specific latent heat of fusion?

Answer 20

Change of state from solid to liquid

Question 21

What is the specific latent heat of vaporisation?

Answer 21

change of state from liquid to vapour/gas

Question 22

Explain how the motion of the molecules in a gas is related to both its temperature and pressure

Answer 22

Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas.

Question 23

What are the factors of pressure on a gas?

Answer 23

Temperature
Volume

Question 24

What is gas pressure?

Answer 24

Gas pressure is the total force exerted by all of the particles in the gas per unit area

Question 25

How can a gas be compressed or expanded?

Answer 25

By pressure changes

Question 26

What is the impact of pressure on gases?

Answer 26

The pressure produces a net force at right angles to the wall of the gas container (or any surface)

Question 27

At a constant temperature, what effect does increasing volume have on the pressure of a gas?

Answer 27

Increasing volume decreases pressure as particles collide less frequently with the walls

Question 28

For a fixed mass of gas held at a constant temperature:

What is the equation that links pressure, volume and constant?

Answer 28

pV = constant

pressure, in pascals, Pa

volume, V, in metres cubed, m3

Question 29

What is work?

Answer 29

Work is the transfer of energy by a force.