Solids, Liquids, Gases Flashcards
Density =
Mass / Volume
Pressure =
Force / Area
In gases and liquids at rest where does the pressure at any point act?
Equally in all directions
How do you get a lower pressure?
Same force applied over a larger area
Pressure difference =
Height x density x gravitational field strength
What is Pressure Difference?
Difference in pressure between two points in a liquid or gas
What is Pressure?
Measure of force being applied to the surface of something
What is Pressure measured in?
Pascals (Pa) or Kilopascal (kPa)
What are the units of density?
g/cm3 or Kg/m3
What are Solids?
- Strong forces of attraction
- Particles close together
- Fixed regular arrangement
- Vibrate In fixed position
- No energy
What are Liquids?
- Weaker forces of attraction
- Particles close together but move past each other
- Form irregular arrangements
- Some energy
- Move in random directions at low speeds
What are Gases?
- No force of attraction
- A lot of energy
- Move in random directions at high speeds
What is Thermal energy store?
Energy in substances thermal energy store is held by its particles in their kinetic energy store
What happens if you heat a liquid?
- Extra energy transferred into particles kinetic energy store
- Move faster
- Big bubbles of gas from in liquid = boiling
What happens if you heat a solid?
- Extra energy makes particles vibrate faster
* Eventually forces between them are partly overcome and start to move around = melting
How can particles near surface of liquid escape and become gas particles?
- If particles are travelling in right direction to escape
- If particles travelling fast enough - have energy in their kinetic energy stores to overcome attractive forces of the other particles
What is Evaporation?
Particles escape from a liquid and become gas particles
Describe an experiment to show that temperature remains constant during changes of state?
- Fill beaker with crushed ice
- Thermometer in beaker + record temperature of ice
- Hear beaker w/ Bunsen burner
- Every 20 secs record temp + state of ice - do until water boils
- Plot graph of temperature against time for experiment
What happens if you cool a substance down?
You reduce the energy of particles
What is Absolute zero?
- Cold as stuff can get
* Start of Kelvin scale of temperature
How do you convert Celsius to Kelvins?
Add 273
What is the Boiling point of water for Celsius and Kelvin?
- 100 degrees celsius
* 373 Kelvin
What is the Particle theory?
- Gases are very small particles which are constantly moving in random directions
- Particles collide with / bounce off each other and the container walls
- If you Increase the temperature of gas, you give particles more energy
What is the temperature of gas (in kelvins) proportional to?
The average energy in the kinetic energy stores of its particles
What happens when gas particles collide with a container of each other?
- They exert a force on it
- Their momentum + direction changes
- In sealed container = smash against its walls, creating an outward pressure
What happens if you heat a gas?
- Particles move faster and have more energy in their kinetic stores
- Particles hit container walls harder + more frequently = larger force = more pressure
What happens if you put the same fixed amount of gas in a bigger container?
- Fewer collisions between gas particles and container walls
- Pressure decreases
What happens if you put the same fixed amount of gas in a smaller container?
When volume reduced: •Particles more squashed up •Hit walls more frequently •Producing a larger force over a small surface area •Pressure increases
What’s the equation for a fixed mass of gas at a constant temperature?
Constant = Pressure x Volume
What is the equation for a gas in a sealed container at a constant volume?
Constant =
Pressure / Temperature(in K)
What is a specific heat capacity of a substance?
The energy required to change the temperature of an object by 1 degrees per kilogram of mass
How can you find the specific heat capacity of water?
- Mass of insulating container
- Mass of container with water
- Difference In mass is the mass of water in the container
- Attach joulmeter to container + electric heater with thermometer
- Measure Temp + turn on power
- When temp increased, turn off power,record temp increase + energy on joulmeter
- Repeat 3 times + find average
