THERMAL PHYSICS

What properties can be used to compare solids, liquids, and gases?

Shape, volume, particle movement, and intermolecular forces

Describe the shape of solids

This is fixed

Describe the shape of liquids

Variable (It takes the shape of the container it’s in)

Describe the shape of gases

Variable (It takes the shape of the container it’s in)

Describe the volume of solids

This is fixed

Describe the volume of liquids

This is fixed

Describe the volume of gases

This expands to fill the container it’s in

Describe the particle movement of solids

These vibrate about their fixed positions 

Describe the particle movement of liquids

These move freely

Describe the particle movement of gases

These move randomly at high speeds

Describe the intermolecular forces of solids

These are strong

Describe the intermolecular forces of liquids

These are weak

Describe the intermolecular forces of gases

These are very weak (Negligible)

What is thermal expansion?

This is the increase in the size of a substance when it is heated, caused by its molecules gaining kinetic energy and moving farther apart.

What are examples of thermal expansion?

1. The expansion of electric cables on a hot sunny day 

2. The creaking sounds of floorboards during fluctuations in temperature. 

3. Construction of bridges with expansion gaps

What is a bimetallic strip?

This is a strip that consists of two different metals joined together.

What is the purpose of the gas laws?

These show the relationship between the properties of a gas

What are the properties of a gas?

Pressure, temperature, and volume

What are the three (3) gas laws?

Boyle’s Law (Links volume and pressure)

Charles’ Law (Links volume and temperature)

Pressure Law (Links pressure and temperature)

State Boyle’s Law

This states that for a fixed mass of gas at constant temperature the volume of the gas is inversely proportional to the pressure. 

What is the formula for Boyle’s Law?

P ∝ 1/V - Pressure is inversely proportional to the volume

P= K 1/V

PV= K - The product of P and V is a constant

P₁V₁ = P₂V₂

What does it mean when two quantities are inversely proportional?

When two quantities are inversely proportional, as one quantity increases, the other decreases. For example, if a gas is compressed, which lowers its volume, the pressure of the gas will increase.

State Charle’s Law

This states that for a fixed mass of gas at constant temperature the volume of the gas is inversely proportional to its absolute (Kelvin) temperature 

What is the formula for Charles’s Law?

V ∝ T - Volume is directly proportional to the temperature

V= KT

V/T= K

V_1/T₁ = V_2/T₂

V₁T₂= V₂T₁

State the pressure law

This states that for a fixed mass of gas at constant volume the pressure of the gas is directly proportional to its absolute (kelvin) temperature.

What is the formula for the pressure law?

P = KT

P/T = K 

P₁T₂= P₂T₁

What is the general gas law and when is it used?

This is the law used to combine all three gas laws. It is used when the temperature, pressure and volume are changing.

What is the formula of the general gas law?

PV/T= K

P₁V₁/T₁ = P₂V₂/T₂

Define the term heat capacity (C)

This is the amount of heat energy required to change the temperature of a substance by 1 degree

What is the formula for finding the heat capacity?

E_H= CΔT

Define the term specific heat capacity (c)

This is the amount of heat energy required to change the temperature of 1 kilogram of a substance by one degree.

What is the formula used to find the specific heat capacity?

E_H= mcΔT

What is the formula used to show the relationship between heat capacity (C) and specific heat capacity (c)?

C=mc

State the specific heat capacity of water?

This is the amount of heat energy required to change the temperature of 1kg of water by 1 degree

What is the value for the specific heat capacity of water?

C_{W= 4200 j /kg /k}

What are the 2 methods used to find the specific heat capacity of a substance?

The method of mixtures and the electrical method

What is the method of mixtures?

This is the method used to find the specific heat capacity of a substance that can be either a solid or liquid 

What is the formula used to calculate the specific heat capacity of a substance when using the methos of mixtures? 

Energy transferred by metal = Energy gained by water  

 M_m C_m Δ T_m= M_w C_W Δ T_w

What is the electrical method?

This is the method used to find the specific heat capacity of a solid such as a block of metal.

What is the formula used to find the specific heat capacity of a substance using the electrical method?

Heat Transferred = Heat gained 

IVt = mcΔt  

Define the term latent heat (Hidden Heat)

This is defined as the energy released or absorbed by a substance during a change in its physical state without changing its temperature.

What is the specific latent heat (L)?

This is the energy required to change the state of 1 kilogram of a substance. 

What is the formula used to find the specific latent heat?

E_H= mL

What is the specific latent heat of fusion? (Solid → Liquid)

                                                                ←

This is the heat energy required to convert 1kg of a solid to 1kg of a liquid at a constant temperature. 

What is the formula used to find the specific latent heat of fusion?

E_H= mL_f

What is the specific latent heat of fusion of water?

This is the heat energy required to convert 1kg of solid ice to 1kg of water at 0°C

What is the value of the specific latent heat of fusion?

340 000 J/kg

What is the specific latent heat of vapourization?

This is the heat energy required to convert 1kg of a liquid to 1kg of a gas/vapour at a constant temperature. 

What is the formula used to find the specific latent heat of vapourization?

E_H= ml_v

What is the specific latent heat of vapourization of water?

This is the heat energy required to convert 1kg of water at 100°C to 1kg of steam/vapour at 100°C.

What is the formula used to find the specific latent heat of vapourization of water?

E_H= ml_v

What is the value of the amount of energy required to convert 1kg of water to 1kg of steam/vapour at 100°C?

l_v= 2,300,000 J/kg OR 2.3 × 10⁶ J/kg

What is a heating curve?

This is a graph used to show how the temperature of a substance changes with time as it is heated.

What is a cooling curve?

This is a graph used to show how the temperature of a substance changes as it is cooled.

Define the term boiling

This is the process by which the molecules of a liquid turns to vapour at a specific temperature. This process occurs at a specific temperature and throughout the liquid.

Define term evaporation 

This is the spontaneous transition of water molecules to the gaseous phase. This process occurs as a result of more energetic molecules leaving the surface of the liquid. Evaporation causes cooling and occurs at any temperature.

What are the factors affecting the rate of evaporation?

1. Temperature

2. Surface area

3. Wind speed

4. Humidity