Solids, Liquids and Gases Flashcards
Density is
Mass per unit volume
Density is measured in
kg/metre cubed
How to calculate density of a liquid
Find measuring cylinder mass
Find measuring cylinder and liquid mass
Difference will be mass of liquid
Read volume of liquid (do this straight on to avoid parallax error)
Find density using the equation
How to calculate the density of a solid
Measure the mass of the solid
either: measure its dimensions if a cuboid
or: immerse in water in a measuring beaker, measuring volume before and after
Difference will be the volume of the solid
Find density using the equation
Pressure is
Force per unit Area
Pressure is measured in
Pascals (Pa)
Pressure at a point in a gas or liquid…
- Acts equally in all directions
- Is perpendicular to the surface
- Is created from particle movement and their collision with the surface
In a liquid, pressure is proportional to…
…depth, density and gravitational field strength
In a liquid, pressure equals
hpg
Gas molecules move…
…rapidly and randomly due to collisions with other gas molecules
Gas exerts pressure on a container due to…
…particle collisions with the surface of the container. The particles rebound, changing direction, therefore changing velocity, therefore changing momentum, therefore they exert a force as Force equals change in momentum over time
For a constant volume, as temperature increases…
…pressure increases as molecules move faster, colliding harder and more frequently
Absolute zero in Kelvin
Zero
Absolute zero in Celsius
-273 Celsius
At a constant temperature, as volume increases…
…pressure decreases
P1 x V1 equals
P2 x V2
P1 x V1 = P2 x V2 is known as
Boyle’s Law
For a gas, temperature in Kelvin is proportional to
average Kinetic energy
Heating a solid or a liquid…
- Increases internal energy leading to
- Increases temperature or Change in State
As temperature rises in a solid, liquid or gas
- Increased energy causes more molecule vibrations leading to
- An increases in Kinetic energy
When a body changes state the energy is used to…
- Make molecules freer from each other, therefore
- Not increasing their Kinetic energy, therefore
- Temperature remains constant
Melting (molecular behaviour)
Molecules in a solid vibrate enough to move from their fixed positions, therefore turning into a liquid
Boiling (molecular behaviour)
Molecules in a liquid gain enough Kinetic energy to break their bonds, becoming separate molecules, turning into a gas
During a change in state…
…temperature remains constant
Evaporation is…
…the escape of higher energy molecules from a liquid surface.
To increase evaporation…
- Increase temperature of liquid
- Increase surface area of liquid
- Provide a draught
Evaporation results in cooling because…
…after higher energy molecules have escaped, the remaining molecules have lower average kinetic energy and therefore a lower average temperature
Specific Heat Capacity is…
…the amount of energy required to raise 1kg of mass by 1 degree Celsius
Evaporation is different from boiling because…
- It is only at the surface
- It can occur at any temperature
Specific Heat Capacity is measure in…
Joules/kgC
Molecular properties of Solids
- Molecules are close
- Molecules are in a regular pattern
- Strong intermolecular forces of attraction
- Molecules vibrate but cannot move
Molecular properties of Liquid
- Molecules are close
- Molecules are in a random arrangement
- Weaker intermolecular forces of attraction
- Molecules move around each other
Molecular properties of Gases
- Molecules are far apart
- Molecules are in a random arrangement
- Very weak intermolecular forces of attraction
- Molecules move quickly and in all directions
