Density is the mass per unit volume of a material.

What units can density be measured in?

g/cm³ (if mass is in g and volume in cm³) or kg/m³ (if mass is in kg and volume in m³).

If a material is more dense than water (1000 kg/m³), it will ______ .

If a material is more dense than water (1000 kg/m³), it will sink .

Why do gases have a lower density than solids of the same mass?

In a gas, the same mass of molecules is spread over a much larger volume , as the molecules are more widely spaced.

True or False? A balloon can be less dense than a small bar of lead despite occupying a larger volume.

True. Density depends on mass per unit volume, so a large but light object can be less dense than a small but heavy one.

Describe the arrangement and movement of particles in a solid .

The particles are closely packed and vibrate about fixed positions.

Describe the arrangement and movement of particles in a liquid .

The particles are closely packed but can flow over one another.

Describe the arrangement and movement of particles in a gas .

The particles are far apart and move randomly .

Gases are highly ______ because there are large gaps between the particles, making them easier to push closer together.

Gases are highly compressible because there are large gaps between the particles, making them easier to push closer together.

Why do solids and liquids have roughly the same density as each other?

In both, the molecules are tightly packed together, even though liquid molecules can push past each other.

Why do gases have a significantly lower density than solids or liquids?

Gas molecules are widely separated , much further apart in each direction than in a solid or liquid.

True or False? A gas has a definite shape and a fixed volume.

False. A gas has no definite shape and no fixed volume — it takes the shape of its container and expands to fill it.

How is the volume of an irregularly shaped object found using a eureka can?

The volume of the water displaced into the measuring cylinder is equal to the volume of the object .

How do you calculate the mass of a liquid when finding its density?

Mass of liquid = mass of cylinder with liquid − mass of empty cylinder.

A digital balance must be ______ before taking a measurement to avoid a systematic error.

A digital balance must be zeroed before taking a measurement to avoid a systematic error.

Give one random error in the experiment to determine density and how it is minimised.

Errors in length measurements ; minimised by taking repeat readings and calculating an average .

Why should an irregular object be lowered carefully into the eureka can?

Dropping it from a height might cause water to splash out , giving an incorrect volume reading.

True or False? Water should be poured into the measuring cylinder while it is on the electric balance.

False. This could lead to an electric shock ; the cylinder should be removed from the balance before adding water.

Melting is when a solid turns into a liquid (e.g. ice to water).

A solid turning directly into a gas is called ______ .

A solid turning directly into a gas is called subliming .

What happens to the mass and number of molecules of a substance when it changes state?

Both stay the same — only the substance's energy changes.

True or False? Changes of state are irreversible, unlike chemical changes.

False. Changes of state are physical changes and are reversible .

A beaker of water left in a room at constant temperature loses mass over 24 hours. Why, and what happens to the total number of water molecules (beaker plus air)?

The mass lost is due to water evaporating into the air; the total number of water molecules stays the same , as none is destroyed — it just changes from liquid to gas.

Define internal energy .

Internal energy is the total energy stored inside a system by the particles that make up the system, due to their motion and positions .

What two forms of energy make up a substance's internal energy ?

Kinetic energy (due to random motion/vibration) and potential energy (due to position relative to each other).

What does a higher temperature indicate about a substance's molecules?

They have a higher average kinetic energy and so move around faster .

On a heating curve, what is happening to a solid's particles as it is heated, before it starts to melt?

Their kinetic energy is increasing, so the temperature rises.

During a change of state, kinetic energy stays ______ while potential energy increases.

During a change of state, kinetic energy stays the same while potential energy increases.

Why does a substance's temperature stay constant during a change of state, even though it is still being heated?

The energy is being used to increase potential energy and break bonds between molecules, rather than increase kinetic energy .

True or False? Heating a substance always increases its temperature.

False. Heating always increases internal energy, but during a change of state this increases potential energy rather than temperature.

Define specific heat capacity .

The amount of energy required to raise the temperature of 1 kg of the substance by 1 °C .

Define specific latent heat .

The amount of thermal energy required to change the state of 1 kg of a substance with no change in temperature .

What is the difference between the specific latent heat of fusion and of vaporisation ?

Fusion is for the solid ↔ liquid change; vaporisation is for the liquid ↔ gas change.

Why does water make a good material for heating homes in radiators?

Water has a very high specific heat capacity , so it remains hot for a long time.

A substance with a ______ specific heat capacity heats up and cools down quickly.

A substance with a low specific heat capacity heats up and cools down quickly.

True or False? Specific heat capacity is used for a change of state, while specific latent heat is used for a change in temperature.

False. It is the other way round: specific heat capacity is for a temperature change in the same state, and specific latent heat is for a change of state with no temperature change.

Define specific heat capacity .

Specific heat capacity is the amount of thermal energy required to raise the temperature of 1 kg of a substance by 1 °C. It is measured in joules per kilogram per degree Celsius (J/kg °C).

What do m and Δ θ represent in the equation Δ Q = mc Δ θ ?

m is the mass of the substance, in kilograms (kg). Δ*θ * is the change in temperature , in degrees Celsius (°C).

The specific heat capacity of water is 4200 J/kg °C. What is the energy transferred when 0.48 kg of water increases in temperature by 0.7 °C?

Δ Q = mc Δ θ = 0.48 × 4200 × 0.7 = 1411.2 J ≈ 1400 J (2 s.f.)

The change in thermal energy, Δ Q , is measured in ______ .

The change in thermal energy, Δ Q , is measured in joules (J) .

True or False? Δ Q represents the change in temperature of a substance.

False. Δ Q represents the change in thermal energy , in joules (J). Δ θ represents the change in temperature.

Define specific latent heat .

Specific latent heat is the amount of thermal energy required to melt or vaporise 1 kg of a substance. It is measured in joules per kilogram (J/kg).

True or False? Evaporating 1 kg of water requires less thermal energy than melting the same mass of ice.

False. Evaporating requires more thermal energy than melting, because vaporisation must fully separate the particles, while fusion only partially overcomes the forces between them.

The specific latent heat of ______ is used for a change between solid and liquid, while the specific latent heat of ______ is used for a change between liquid and gas.

The specific latent heat of fusion is used for a change between solid and liquid, while the specific latent heat of vaporisation is used for a change between liquid and gas.

The specific latent heat of fusion of stearic acid is 199 000 J/kg. What is the energy transferred to the surroundings as 0.60 kg of stearic acid changes state from liquid to solid?

Q = mL = 0.60 × 199 000 = 119 400 J

Define thermal equilibrium .

Thermal equilibrium is reached when an object has cooled to room temperature and no longer loses heat to its surroundings.

GCSEPhysicsEdexcelFlashcards14. Particle ModelStates of Matter & Thermal Capacity

States of Matter & Thermal Capacity (Edexcel GCSE Physics): Flashcards

Exam code: 1PH0

1/66

0Still learning

Know0

FrontDensity
Define density.

Was this flashcard helpful?

Cards in this collection (66)

Define density.
Density is the mass per unit volume of a material.
Write the equation that links density, mass and volume.
$ρ = \frac{m}{V}$
where ρ = density, m = mass and V = volume.
What units can density be measured in?
g/cm³ (if mass is in g and volume in cm³) or kg/m³ (if mass is in kg and volume in m³).
If a material is more dense than water (1000 kg/m³), it will ______.
If a material is more dense than water (1000 kg/m³), it will sink.
Why do gases have a lower density than solids of the same mass?
In a gas, the same mass of molecules is spread over a much larger volume, as the molecules are more widely spaced.
True or False?
A balloon can be less dense than a small bar of lead despite occupying a larger volume.
True.
Density depends on mass per unit volume, so a large but light object can be less dense than a small but heavy one.
When converting from a larger unit to a smaller unit (e.g. metres to centimetres), do you multiply or divide?
Multiply.
Describe the arrangement and movement of particles in a solid.
The particles are closely packed and vibrate about fixed positions.
Describe the arrangement and movement of particles in a liquid.
The particles are closely packed but can flow over one another.
Describe the arrangement and movement of particles in a gas.
The particles are far apart and move randomly.
Gases are highly ______ because there are large gaps between the particles, making them easier to push closer together.
Gases are highly compressible because there are large gaps between the particles, making them easier to push closer together.
Why do solids and liquids have roughly the same density as each other?
In both, the molecules are tightly packed together, even though liquid molecules can push past each other.
Why do gases have a significantly lower density than solids or liquids?
Gas molecules are widely separated, much further apart in each direction than in a solid or liquid.
True or False?
A gas has a definite shape and a fixed volume.
False.
A gas has no definite shape and no fixed volume — it takes the shape of its container and expands to fill it.
What is the resolution of a micrometer?
0.001 mm.
How is the volume of an irregularly shaped object found using a eureka can?
The volume of the water displaced into the measuring cylinder is equal to the volume of the object.
How do you calculate the mass of a liquid when finding its density?
Mass of liquid = mass of cylinder with liquid − mass of empty cylinder.
A digital balance must be ______ before taking a measurement to avoid a systematic error.
A digital balance must be zeroed before taking a measurement to avoid a systematic error.
Give one random error in the experiment to determine density and how it is minimised.
Errors in length measurements; minimised by taking repeat readings and calculating an average.
Why should an irregular object be lowered carefully into the eureka can?
Dropping it from a height might cause water to splash out, giving an incorrect volume reading.
True or False?
Water should be poured into the measuring cylinder while it is on the electric balance.
False.
This could lead to an electric shock; the cylinder should be removed from the balance before adding water.
Define melting.
Melting is when a solid turns into a liquid (e.g. ice to water).
What is it called when a liquid turns into a solid?
Freezing.
What is it called when a gas turns into a liquid?
Condensing.
A solid turning directly into a gas is called ______.
A solid turning directly into a gas is called subliming.
What happens to the mass and number of molecules of a substance when it changes state?
Both stay the same — only the substance's energy changes.
True or False?
Changes of state are irreversible, unlike chemical changes.
False.
Changes of state are physical changes and are reversible.
A beaker of water left in a room at constant temperature loses mass over 24 hours. Why, and what happens to the total number of water molecules (beaker plus air)?
The mass lost is due to water evaporating into the air; the total number of water molecules stays the same, as none is destroyed — it just changes from liquid to gas.
Define internal energy.
Internal energy is the total energy stored inside a system by the particles that make up the system, due to their motion and positions.
What two forms of energy make up a substance's internal energy?
Kinetic energy (due to random motion/vibration) and potential energy (due to position relative to each other).
What does a higher temperature indicate about a substance's molecules?
They have a higher average kinetic energy and so move around faster.
On a heating curve, what is happening to a solid's particles as it is heated, before it starts to melt?
Their kinetic energy is increasing, so the temperature rises.
During a change of state, kinetic energy stays ______ while potential energy increases.
During a change of state, kinetic energy stays the same while potential energy increases.
Why does a substance's temperature stay constant during a change of state, even though it is still being heated?
The energy is being used to increase potential energy and break bonds between molecules, rather than increase kinetic energy.
True or False?
Heating a substance always increases its temperature.
False.
Heating always increases internal energy, but during a change of state this increases potential energy rather than temperature.
Define specific heat capacity.
The amount of energy required to raise the temperature of 1 kg of the substance by 1 °C.
Define specific latent heat.
The amount of thermal energy required to change the state of 1 kg of a substance with no change in temperature.
What is the difference between the specific latent heat of fusion and of vaporisation?
Fusion is for the solid ↔ liquid change; vaporisation is for the liquid ↔ gas change.
Why does water make a good material for heating homes in radiators?
Water has a very high specific heat capacity, so it remains hot for a long time.
A substance with a ______ specific heat capacity heats up and cools down quickly.
A substance with a low specific heat capacity heats up and cools down quickly.
What are the units of specific latent heat?
Joules per kilogram (J/kg).
True or False?
Specific heat capacity is used for a change of state, while specific latent heat is used for a change in temperature.
False.
It is the other way round: specific heat capacity is for a temperature change in the same state, and specific latent heat is for a change of state with no temperature change.
Define specific heat capacity.
Specific heat capacity is the amount of thermal energy required to raise the temperature of 1 kg of a substance by 1 °C. It is measured in joules per kilogram per degree Celsius (J/kg °C).
Write the equation linking change in thermal energy, mass, specific heat capacity and change in temperature.
$Δ Q = m c Δ θ$
What do m and Δθ represent in the equation ΔQ = mcΔθ?
m is the mass of the substance, in kilograms (kg). Δ*θ* is the change in temperature, in degrees Celsius (°C).
The specific heat capacity of water is 4200 J/kg °C.
What is the energy transferred when 0.48 kg of water increases in temperature by 0.7 °C?
ΔQ = mcΔθ = 0.48 × 4200 × 0.7 = 1411.2 J ≈ 1400 J (2 s.f.)
The change in thermal energy, ΔQ, is measured in ______.
The change in thermal energy, ΔQ, is measured in joules (J).
True or False?
ΔQ represents the change in temperature of a substance.
False.
ΔQ represents the change in thermal energy, in joules (J). Δθ represents the change in temperature.
Define specific latent heat.
Specific latent heat is the amount of thermal energy required to melt or vaporise 1 kg of a substance. It is measured in joules per kilogram (J/kg).
Write the equation linking thermal energy, mass and specific latent heat.
$Q = m L$
True or False?
Evaporating 1 kg of water requires less thermal energy than melting the same mass of ice.
False.
Evaporating requires more thermal energy than melting, because vaporisation must fully separate the particles, while fusion only partially overcomes the forces between them.
The specific latent heat of ______ is used for a change between solid and liquid, while the specific latent heat of ______ is used for a change between liquid and gas.
The specific latent heat of fusion is used for a change between solid and liquid, while the specific latent heat of vaporisation is used for a change between liquid and gas.
The specific latent heat of fusion of stearic acid is 199 000 J/kg.
What is the energy transferred to the surroundings as 0.60 kg of stearic acid changes state from liquid to solid?
Q = mL = 0.60 × 199 000 = 119 400 J
Define thermal equilibrium.
Thermal equilibrium is reached when an object has cooled to room temperature and no longer loses heat to its surroundings.
Name the three processes by which thermal energy transfers from hotter to cooler areas.
Conduction, convection and radiation.
Why are materials such as wool and cotton good thermal insulators?
They are low density and contain pockets of trapped air, which is a poor conductor of heat, reducing the rate of heat loss.
How does trapped air in an insulating material reduce heat loss by convection?
Trapped air is unable to move around, so it cannot form convection currents.
Covering a hot object with a ______ (non-metal) coating reduces heat loss by radiation, because such materials are poor ______ of radiation.
Covering a hot object with a shiny (non-metal) coating reduces heat loss by radiation, because such materials are poor emitters of radiation.
True or False?
Putting a lid on a hot drink reduces heat loss by convection.
True.
A lid traps air and prevents it from moving away, reducing heat loss by convection.
What quantities are measured in the experiment to determine the specific heat capacity of water?
The energy supplied (read from a joulemeter), the temperature of the water, and the mass of the water.
How is the energy supplied to an immersion heater measured?
It is read directly from a joulemeter connected to the heater, giving the energy transferred in joules (J).
In the experiment to determine the specific heat capacity of water, what quantities are plotted on the graph, and what does the gradient represent?
Energy supplied (y-axis) is plotted against temperature change × average mass (x-axis). The gradient of the straight-line region equals the specific heat capacity of water.
In the experiment to determine the specific heat capacity of water, why should the gradient only be taken from the straight-line region of the graph?
Before this point, the energy supplied is being used to heat the immersion heater itself, not the water, so this region does not give the true specific heat capacity.
The temperature-time graph for melting ice shows a ______ section while the ice is melting.
The temperature-time graph for melting ice shows a flat section while the ice is melting.
True or False?
In the experiment to heat ice and measure its temperature as it melts, the ice-water mixture should be stirred constantly during heating.
True.
Stirring reduces random error by keeping the temperature even throughout the mixture.
Give one safety consideration when carrying out the experiment to determine the specific heat capacity of water.
A safety consideration of this experiment is:
- The immersion heater gets very hot, so avoid touching it and use a heatproof mat
- The immersion heater must be connected to a direct current supply
- The beaker may be unstable, so a clamp stand should be used
- Goggles must be worn
- Students should remain standing throughout the experiment

Sign up to unlock flashcards

By signing up you agree to our Terms and Privacy Policy

Previous:Electromagnetic InductionNext:Particle Model & Pressure