Density is the mass per unit volume of a material.

If the mass is measured in kg and the volume in m³, then the density will be in ______ .

If the mass is measured in kg and the volume in m³, then the density will be in kg m⁻³ .

A material has a density greater than 1000 kg m⁻³. What will happen if it is placed in water?

It will sink , because it is denser than water (1000 kg m⁻³).

True or False? A gas takes up a much smaller volume than the same mass of solid or liquid.

False. A gas takes up a much larger volume than the same mass of solid or liquid, because its particles are far more spread out.

Why does a gas have a lower density than a solid or liquid of the same substance?

Because gas particles are much further apart , so fewer particles occupy a given volume.

State the difference between mass, weight and density.

Mass is the amount of matter in an object, measured in kg. Weight is the force acting on an object due to gravity, measured in N. Density is the amount of matter in a fixed volume, measured in kg m⁻³.

Put solids, liquids and gases in order of relative density, from highest to lowest.

Solid (highest) > liquid > gas (lowest), because particles are progressively less closely packed.

Define the particle model .

The particle model describes the arrangement and movement of particles in a substance.

What two things does the particle model help to explain?

The different states of matter (solid, liquid, gas) and physical properties such as differences in density .

Describe the arrangement and movement of particles in a solid.

In a solid , particles are closely packed and vibrate about fixed positions.

Describe the arrangement and movement of particles in a liquid.

In a liquid , particles are closely packed but can flow over one another.

Describe the arrangement and movement of particles in a gas.

In a gas , particles are far apart and move randomly .

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

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

Why do solids and liquids have roughly the same density?

In both, the molecules are tightly packed together; in a liquid, the molecules simply have enough energy to push past each other .

True or False? Gases have a similar density to solids and liquids.

False. Gases have significantly lower density than solids and liquids, because their molecules are much more widely separated.

How does the density of a typical gas compare to the density of the same substance as a solid or liquid?

A gas typically has a density around one-thousandth (1/1000) of the density of a solid or liquid, for example water is 1000 kg/m³ while air is 1.3 kg/m³.

How is the volume of an irregularly shaped object determined experimentally?

By displacement - the object is lowered into a eureka can full of water, and the volume of water displaced (collected in a measuring cylinder) equals the volume of the object .

How is the mass of a liquid found in the density practical?

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

The eureka can must be completely ______ before the object is added, so that all the displaced water exits the spout.

The eureka can must be completely full before the object is added, so that all the displaced water exits the spout.

Why should the digital balance be zeroed before each measurement?

To remove a systematic error , ensuring the balance reads only the mass of the object or liquid being measured.

True or False? Anomalous results should be included when calculating an average in this practical.

False. Anomalous results should be excluded from any averages calculated.

Give one safety precaution for this practical.

Handle glassware carefully, and stand up throughout the experiment so you can react quickly to spills; water should not be poured into a cylinder while it is on the electric balance, as this could cause an electric shock .

Melting is when a solid turns into a liquid as energy is transferred to the system (e.g. ice to water).

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

Both stay the same - the number of molecules doesn't change, so the mass doesn't change either.

Are changes of state reversible or irreversible?

Changes of state are physical changes and are reversible (unlike chemical changes).

______ is when a gas turns into a liquid, as energy is transferred away from the system.

Condensing is when a gas turns into a liquid, as energy is transferred away from the system.

What happens to energy when a liquid freezes into a solid?

Energy is transferred away from the system.

True or False? When ice melts into water, the water molecules themselves break apart.

False. The molecules don't separate or change; melting is a physical change , so water molecules remain water molecules whether solid, liquid or gas.

Why might the mass of a liquid decrease as it evaporates in an open container?

Because gas particles can escape from an open container as the liquid changes into a gas.

GCSEPhysicsAQAFlashcardsParticle Model of MatterChanges of State & the Particle Model

Changes of State & the Particle Model (AQA GCSE Physics): Flashcards

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Define density.

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Cards in this collection (33)

Define density.
Density is the mass per unit volume of a material.
What equation relates density, mass and volume?
$ρ = \frac{m}{V}$
where ρ is density, m is mass and V is volume.
If the mass is measured in kg and the volume in m³, then the density will be in ______.
If the mass is measured in kg and the volume in m³, then the density will be in kg m⁻³.
A material has a density greater than 1000 kg m⁻³. What will happen if it is placed in water?
It will sink, because it is denser than water (1000 kg m⁻³).
True or False?
A gas takes up a much smaller volume than the same mass of solid or liquid.
False.
A gas takes up a much larger volume than the same mass of solid or liquid, because its particles are far more spread out.
Why does a gas have a lower density than a solid or liquid of the same substance?
Because gas particles are much further apart, so fewer particles occupy a given volume.
State the difference between mass, weight and density.
Mass is the amount of matter in an object, measured in kg. Weight is the force acting on an object due to gravity, measured in N. Density is the amount of matter in a fixed volume, measured in kg m⁻³.
Put solids, liquids and gases in order of relative density, from highest to lowest.
Solid (highest) > liquid > gas (lowest), because particles are progressively less closely packed.
Define the particle model.
The particle model describes the arrangement and movement of particles in a substance.
What two things does the particle model help to explain?
The different states of matter (solid, liquid, gas) and physical properties such as differences in density.
Describe the arrangement and movement of particles in a solid.
In a solid, particles are closely packed and vibrate about fixed positions.
Describe the arrangement and movement of particles in a liquid.
In a liquid, particles are closely packed but can flow over one another.
Describe the arrangement and movement of particles in a gas.
In a gas, particles are far apart and move randomly.
Gases are highly ______ because there are large gaps between the particles, making it easier to push them closer together.
Gases are highly compressible because there are large gaps between the particles, making it easier to push them closer together.
Why do solids and liquids have roughly the same density?
In both, the molecules are tightly packed together; in a liquid, the molecules simply have enough energy to push past each other.
True or False?
Gases have a similar density to solids and liquids.
False.
Gases have significantly lower density than solids and liquids, because their molecules are much more widely separated.
How does the density of a typical gas compare to the density of the same substance as a solid or liquid?
A gas typically has a density around one-thousandth (1/1000) of the density of a solid or liquid, for example water is 1000 kg/m³ while air is 1.3 kg/m³.
What is the resolution of a digital balance typically used in the density practical?
0.01 g.
Which piece of equipment would you use to measure the dimensions of a small object to a resolution of 0.01 mm?
Vernier callipers.
How is the volume of an irregularly shaped object determined experimentally?
By displacement - the object is lowered into a eureka can full of water, and the volume of water displaced (collected in a measuring cylinder) equals the volume of the object.
How is the mass of a liquid found in the density practical?
Mass of liquid = mass of cylinder with the liquid − mass of the empty cylinder.
The eureka can must be completely ______ before the object is added, so that all the displaced water exits the spout.
The eureka can must be completely full before the object is added, so that all the displaced water exits the spout.
Why should the digital balance be zeroed before each measurement?
To remove a systematic error, ensuring the balance reads only the mass of the object or liquid being measured.
True or False?
Anomalous results should be included when calculating an average in this practical.
False.
Anomalous results should be excluded from any averages calculated.
Give one safety precaution for this practical.
Handle glassware carefully, and stand up throughout the experiment so you can react quickly to spills; water should not be poured into a cylinder while it is on the electric balance, as this could cause an electric shock.
Define melting.
Melting is when a solid turns into a liquid as energy is transferred to the system (e.g. ice to water).
What happens to the number of molecules and the mass of a substance when it changes state?
Both stay the same - the number of molecules doesn't change, so the mass doesn't change either.
Are changes of state reversible or irreversible?
Changes of state are physical changes and are reversible (unlike chemical changes).
______ is when a gas turns into a liquid, as energy is transferred away from the system.
Condensing is when a gas turns into a liquid, as energy is transferred away from the system.
Name the change of state in which a solid turns directly into a gas.
Sublimating.
What happens to energy when a liquid freezes into a solid?
Energy is transferred away from the system.
True or False?
When ice melts into water, the water molecules themselves break apart.
False.
The molecules don't separate or change; melting is a physical change, so water molecules remain water molecules whether solid, liquid or gas.
Why might the mass of a liquid decrease as it evaporates in an open container?
Because gas particles can escape from an open container as the liquid changes into a gas.

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