P6 Flashcards
Liquid to gas
Vaporisation or evaporation
Gas to liquid
Condensation
Liquid to solid
Freezing
Solid to liquid
Melting
Solid to gas
Sublimation
Gas to solid
Desublimation or deposition
What does internal energy equal
Potential energy + kinetic energy
Specific latent heat
Is the amount of energy needed to change the unit of mass of a pure substance
Note:
When you heat or cool down a material you only ever change the potential enrrgy or kinetic energy at a time, never both
Equation for energy supplied to or lost by the body
E= mass of body (kg) X specifc latent heat (J/kg)
What does a joulemeter do
Measures electrical energy
Equation for electrical energy
E = ITV
I - current, T - time, V - voltage
In a solid, what causes the particles to remain in the same fixed position
Because there is a strong force of attraction between the particles
What happens to a solid when the particles are given more energy
The particles will vibrate more and if given enough energy, they can brake away from the force and change state into a liquid
Why is there movement from particles in a liquid
The forces of attraction in a liquid is weaker than a solid meaning the particles are not strong enough to stay in a rigid structure but will not leave the substances surface
The forces of attraction in a gas
Extremely weak enabling particles to mvie around at a high speed
What happens when a gas is heated (given more energy)
Its particles gain more kinetic energy and move faster. The particles therefore collide with the surfaces more and with more force
What is internal energy
Measure of how much energy a substance has. Made up of 2 different stores of energy: potential and kinetic energy
What is brownian motion
Movement of particles in a solid liquid or gas
How does brownian motion change in a solid liquid or gas
When the particles are heated up or cooled down, resulting in the particles losing or gaining energy and changes the brownian motion
How to measure the density of a liquid
Measure the mass of an empty beaker using a balance. Remove the beaker from the balance and pour in the liquid from the measuring cylinder. Weigh the mass of beaker and water and calculate the difference to measure the density of the liquid. Then use equation densitiy = mass / volume
Equation for density
Mass / volume
Equipment for eureka can experiment
Measuring cylinder, eureka can, beaker, irregular object, thread and water and top pan balance
How to complete eureka can experiment
Weigh object on top pan balance, fill can with water and place irregular object (on a string) into the beaker, measure volume of water displaced in measuring cylinder then use equation to find density
Latent heat
The energy transferred to a substance when it chsnges its state is called latent heat
Fusion
Sometimes used to describe melting because different solids may join together when melt
Flat section of a temperature-time graph:
Melting or boiling point if a substance
What density objects float in water?
Ones with a density less than water (<1000kg/m)
Heating a substance (example):
When water in a kettle boils, the water turns to steam (water in a gaseous state)
Conservation of mass
When a substance changes state, the number of particles in the substance is unchanged, therefore the mass is the same
Example of conservation of mass:
When ice melts, the water it turns into has the same mass, so the mass is unchanged
Energy of a solid:
Least energetic of the states of matter
Energy of liquid:
More energetic than a solid
Energy of gas:
Most energetic out of the states of matter
How are melting and boiling points affected?
-By impurities in the substance
-e.g. melting point of water is lower if you add salt
What happens when pure ice is heated?
Its temperature stays at 0 degrees until all the ice has melted.
What happens when water is heated?
Its temperature stays at 100 degrees after heating and boiling at atomspheric pressure
How to calculate Temperature of water:
1) Increases until it reaches 0 degrees when the ice starts to melt at 0
2) stays constant at 0 degrees until the ice has melted
3) increases from 0-100 degrees
4) stays constant at 100 detrees as the water turns to steam
When a liquid is below its boiling point…
Evaporation happens at its surface
What is needed to melt a liquid or boil a solid?
Energy
Internal energy
The Energy of the particles that is caused by their individual motions and positions (caused by potential and kinetic energy)
What happens when you increase the temperature of a gas?
The average speed of its particles increase
What does an increase in temperature do to its pressure?
It increases it
What does it mean if a particle has a larger momentum?
It means that they exert a larger force when they collide with the container
What does the density of an object depends on?
What its made of and how the particles are arranged
What happens if you reverse the change of a state?
The substance will return to its original form and get back its original properties
How does a change of state occur
- if the substance is heated enough,the particles will have enough energy in their kinetic energy stores to break the bonds holding them together
What does heating the system do?
Tranfers energy to its particles (they gain kinetic energy and move faster), increasing the internal energy
