P6 Flashcards
What is density?
The density of a substance is defined as it’s mass per unit volume
What are the properties of a dense material?
A dense material has it’s particles packed tightly together
What are the properties of a less dense material?
The particles are more spread out and if you compress the material, it’s particles would move closer together and it would become more dense
What is the formula for density?
P = m ( kg ) / v ( m3 )
If an object is more dense than the water that it’s in it will…..
Sink
Define the characteristics of a solid
Strong forces of attraction hold the particles close together in a fixed, regular arrangement.
The particles don’t have much energy so they can only vibrate about their fixed positions.
The density is generally highest in this state as the particles are closest together
What are the characteristics of a liquid?
There are weaker forces of attraction between the particles.
The particles are close together, but can move past each other, and form irregular arrangements.
They have more energy than the particles in a solid - they move in random directions at low speeds, Liquids are generally less dense than solids.
What are the characteristics of a gas?
There are almost no forces of attraction between the particles.
The particles have more energy than in liquids and solids - they’re free to move, and travel in random direction at high speeds.
Gases are generally less dense than liquids - they have low densities.
How do you find the density of a solid object? Practical
-measure the objects mass
-if it’s a regular solid start by measuring it’s length, height and width and then calculate it’s volume
-for an irregular solid, you find it’s volume by submerging it in a eureka can filled with water. The water displaced by the object will be transferred to a measuring cylinder
-record the volume of water in the measuring cylinder - this is the volume of the solid
-then divide it’s mass by the volume
What is internal energy?
Internal Energy is the Energy Stored by the Particles in a substance
What is the internal energy of a system?
The internal energy of a system is the total energy that its particles have in their kinetic and potential energy stores.
How can you increase the internal energy of a substance? And what can this lead to?
By Heating the system, it transfers energy to its particles (they gain energy in
their kinetic stores and move faster), increasing the internal energy.
This leads to a change in temperature or a change in state. If the temperature changes, the size of the change depends on the mass of the substance, what it’s made of (its specific heat capacity) and the energy input.
A change in state occurs if the substance is heated enough - the particles will have
enough energy in their kinetic energy stores to break the bonds holding them together.
Why does the number of particles not change when changing state?
The number of particles doesn’t change - they’re just arranged differently.
This means mass is conserved - none of it is lost when the substance changes state.
Liquid to solid =
Freezing
Solid to liquid =
Melting
Liquid to gas =
Boiling / evaporating
Gas to liquid =
Condensation
Solid to gas =
Sublimation
Gas to solid =
Desublimation
The random motion of tiny particles in a fluid is called…..
Brownian motion
When does the internal energy of a substance go down?
When a substance is condensing or freezing, bonds are forming between particles, which releases energy.
This means the internal energy decreases, but the temperature doesn’t go down until all the substance has turned to liquid (condensing) or a solid (freezing).
What is specific latent heat?
Specific Latent Heat is the Energy Needed for a 1 kg Mass to Change State without changing it’s temperature
For freezing and condensing, what is the energy that gets released ?
Specific latent heat is the energy released by a change in state
What is the specific latent heat for changing between a solid and a liquid ?
Specific latent heat of fusion
