SOLIDS, LIQUIDS AND GASES Flashcards
relationship between density, mass and volume:
density= mass/ volume
relationship between pressure, force and area:
pressure= force/ area
where does the pressure at a point in a gas or liquid at rest act?
equally in all directions
relationship between pressure difference, height, density and gravitational field strength:
pressure difference= height x density x gravitational field strength
P2 why will a heating system change the energy stored within the system?
a substance must absorb heat energy so that it can melt or boil
P2 arrangement and motion of particles in a solid:
- tightly packed
- fixed pattern
- vibrate about fixed positions
P2 arrangement and motion of particles in a liquid:
- tightly packed
- can slide over each other
P2 arrangement and motion of particles in a gas:
- free to move
- spread out
- move with rapid, random motion
P2 what is specific heat capacity?
- energy required to change the temperature of an object by one degree celsius per kilogram of mass
P2 relationship between change in thermal energy, mass, specific heat capacity, change in temperature:
Change in thermal energy [J] = Mass [kg] x Specific heat capacity [J/kg 0C] x Change in temperature [0C]
why do gases exert a pressure on the walls of a container?
- they have a random motion
- exert a force and hence a pressure on the walls of a container
what is the absolute 0 of temperature?
-273 degrees celsius
what is a kelvin?
-273 degrees celsius
why does an increase in temperature result in an increase in the average speed of gas molecules?
- their kinetic energy increases
what is a Kelvin temperature of gas proportional to?
- the average kinetic energy of its molecules
why is, for a fixed amount of gas:
- pressure and volume at a constant temperature
- pressure and Kelvin temperature at constant volume
- As you heat the gas, the kinetic energy of the particles increases, and thus so does their average speed.
- This means more collisions per second with the walls, and they exert a larger force on the wall.
- This causes in the total pressure being exerted by the particles to rise.
- If temperature is constant, the average speed of the particles is constant.
- If the same number of particles is placed in a container of smaller volume they will hit the walls of the container more often.
- More collisions per second means that the particles are exerting a larger force on the wall over the same time, so average force exerted on the walls has increased.
relationship between the pressure and Kelvin temperature of a fixed mass of gas at constant volume:
P1/T1 = P2/T2
relationship between the pressure and volume of a fixed mass of gas at constant temperature:
p1V1=p2V2
how to convert kelvin into celsius:
C = K- 273
what is Brownian motion?
- large particles move randomly
- because tiny particles are hitting them
- tiny particles are not visible
example of Brownian motion:
pollen suspended in water
using ideas about particles, explain how air inside a container exerts pressure (3 marks):
- collide with one another and walls of the container
- (bombarding particles) exert a force on walls of container
- pressure is force on an area
