P3 Flashcards
What is the particle theory also known as?
Kinetic theory
What happens when atoms emit electromagnetic radiation?
electrons drop to a lower energy level (closer to the nucleus)
What happens when atoms absorb electromagnetic radiation?
electrons move to a higher energy level (further away from the nucleus)
Describe a solid
- strong forces of attraction between particles
- the particles are held tightly against one & other in a fixed position creating a fixed structure
- definite shape and volume
- particles are able to vibrate in their fixed positions
What happens when a solid is heated?
melting
- particles gain more energy and vibrate more which weakens the bonds between them
- once the solid reaches the melting point its bonds would be broken so it can flow
Describe a liquid
- weak forces of attraction between particles
- free to move but the particles tend to stick together
- have a definite volume but their shape can change, allows them to flow and fill a container
What happens when a liquid is heated?
Evaporation
- particles gain kinetic energy so they move around faster
- boiling point- liquid becomes a gas
Describe a gas
- very weak forces of attraction
- free to move around
- do not have a definite shape or volume and always fill a container
- constantly moving with random motion (any direction)
What happens when gas is heated?
- it could expand (in an expandable container)
- the pressure will increase (in a fixed container)
What is it called when a gas is cooled down?
condensation
What is it called when a liquid is cooled down?
Freezing
What is it called when a substance goes from a solid to a gas?
sublimation
When working in a closed system what do changes in state do?
- do not change the mass
- changes the density of the substance:
- solid = highest density
- liquid = lower density
- gas = lowest density
What kind of change is a change in state?
physical- the material recovers its original properties if the change is reversed
What does pressure produce in a gas?
a net force at right angles to the wall of the gas container
equation for a fixed mass of gas held at a constant temperature?
pV= constant
What is pressure measured in?
Pascals
What does doing work on a gas do?
increases the internal energy of the gas and can cause an increase in the temperature of the gas
What is the equation for density?
mass/volume
mass- kg
volume- m3
How do you calculate the density of a solid?
- find the mass by placing it on a mass
- for regular shapes, measure and multiply the length, width and height
- mass/volume
How do you calculate the density of an irregular object?
- Fill the Eureka can (displacement) with water, directly in line with the spout
- place a measuring cylinder beneath the spout
- measure and record the mass of the solid using a balance
- tie string around the object and immerse it into the can
- the volume of displaced water= volume of the object
- calculate density using mass/volume
How do you calculate the density of a liquid?
- place an empty measuring cylinder onto a balance and zero the balance
- pour some of the liquid into measuring cylinder (e.g. 10ml) and record the mass
- divide the mass by the volume
- larger the volume → more accurate density (because it minimises the effects of uncertainty)
How does heating change the energy stored within a system?
- increases the energy of the particles that make up the system
- either raises the temperature or produces a change of state
What is specific latent heat?
The amount of energy required to change the state of 1kg of the substance with no change in temperature
What is the equation for specific latent heat?
E= mL
energy- joules/J
m- kg
L- J/Kg
What are the two types of specific latent heat?
specific latent heat of vaporisation = liquid to gas
specific latent heat of fusion =
solid to liquid
