Topic 1 - Heating and Cooling

How many sig. fig. for the final answer should there be?

3 significant figures

How many sig. fig. for the final answer should there be if its an estimation?

2 significant figures

What counts as an estimation?

reading from a graph, table, description

What are the significant figures rules?

Not significant: zero for cosmetic purpose (0.00)
Not significant: zero used only to locate the decimal point (0.004)
Significant: all nonzero integers
Significant: all zeros between nonzero numbers (0.04004)
Significant: zeros at the end of a number to the right of decimal point (0.4500)

What to remember when converting to significant figures?

1. remember to round
2. remember S.I units

What are the S.I units?

kilograms, metres, seconds, m/s, newtons, litres, kelvin

What is the kinetic theory \=

Kinetic theory \= energy of movement

What does the kinetic theory state?

Kinetic theory states that they tiny particles in all forms of matter are in constant motion

What is the total energy a combination of?

The total energy is a combination of Kinetic energy (move/vibrate at speed) and Potential energy (by moving further from their position of equilibrium)

How can there be a change in state?

By breaking the strong inter-particle forces between atoms

What does increasing the temperature causes the particles...

1. to vibrate more (as kinetic energy increases)
2. to move further apart (as potential energy increases)

What does increasing the temperature cause?

the material to expand when heated (gains energy) and contracts when cooled (loses energy)

What is internal energy?

Internal energy is the amount of kinetic energy available and the amount of potential energy stored within the isolated system

What is temperature?

Temperature is the measure of heat transfer or the average energy in the system and is expressed in terms like Celsius or Kelvin

What is heat?

Heat is the transfer of thermal energy from one object to another as the result of a difference of temperature

What is absolute zero?

0 Kelvin \= -273C

What is 1K increase in degrees celsius?

1C increase

How to go from kelvin to celsius

-273

How to go from celsisus to kelvin

+273

What is heat capacity?

The heat capacity of a body is the quantity of thermal energy absorbed by it for 1K increase in its temperature

What is specific heat capacity?

The specific heat capacity of a substance is the amount of heat required to raise the temperature of 1.0kg of that substance by 1.0K

5kg of water - heat capacity and specific heat capacity

Heat capacity \= 20900 (5*4180)
Specific heat capacity \= 4180

What is quantity of heat energy equal to?

Q(j) \= M(kg) * c(J/kgK) * cT (K)
Q \= MCT

What is water's specific heat capacity?

4180

What is ice's specific heat capacity?

2100

What is paraffin's heat capacity?

2140

What is the change of state equation?

Q \= mL

What is latent heat?

energy (heat) is continually applied, however, instead of a change in temperature, there is a change in state. The applied heat is absorbed by the particles, as potential energy, as they move further apart from each other; weakening and eventually breaking bonds

What is the latent heat of fusion?

The amount of heat (energy) required to convert 1kg of a Solid completely into a liquid (or a liquid into a solid), without a change in temperature occurring

What is the latent heat of vaporisation?

The energy required to convert 1kg of a liquid completely into vapour (or vapour into liquid), without a change in temperature occurring

What is latent heat's units?

J Kg-1

What is energy units?

J (joules)

What is thermal equilibrium?

Where two or more objects of different temperature are placed in an isolated system. The objects will each gain or lose internal (kinetic and potential) energy to the other system until both have an equal temperature

what is the thermal equilibrium equation?

heat lost by material 1 + heat gained by material 2 \= 0

What is the law of conservation of energy?

Energy is neither created nor destroyed, however it is transferred or transformed.

What is closed systems?

closed systems are systems isolated from their environment. Eg a calorimeter

What is open systems?

Open systems are systems that allow energy to move across boundaries

Heat is...

transferred or transformed

Cold is not...

a form of energy transfer. It is the result of a lack of energy

Cold can only..

take or give energy

what is the efficiency equation?

energy output/energy input * 100

What is conduction?

transfer of thermal energy by direct contact of particles

solid/liquids/gases

What is radiation?

transfer of energy by electromagnetic waves

does not require matter

What is convection?

transfer of thermal energy through currents

liquids and gases

What is an example of conduction?

metal handle on a camp oven

What is an example of radiation?

bonfire, heat lamp and light bulb

What is an example of convection?

boiling water

How does conduction work?

Valence electrons of metal atoms are free to move and transfer energy quickly throughout the metal

How does radiation work?

Radiant energy that is absorbed becomes thermal energy.
All matter can radiate energy. However, energies higher than the light spectrum absorb and release through black objects

How does convection work?

As liquids and gases gain thermal energy, they expand and decrease in density, moving to an area of equal density

what two factors affect the thermal conductivity?

1. the space between the particles.
2. the availability of free electrons

How does the space between particles affect thermal conductivity?

gas particles are relatively spaced apart. Therefore the particles have fewer opportunities to bump into each other or other objects to transfer thermal energy

How does the availability of free electrons affect thermal conductivity?

free electrons often aid in transferring the energy to ions faster than normal conduction. This is why thermal energy transfers faster in metals compared to wood or plastic

What is superfluid?

a low temperature device with zero viscosity, allowing it to move through any pores of a substance

What is superconductor?

a low temperature device with zero resistance, usually occurs when a material reaches it's critical temperature