pressure + gas molecules Flashcards
1
Q
to find the density of liquid
A
- Measure the mass of the object using a balance (press tare no zero error)
Place a known amount of water into a measuring cylinder
Submerge the object into the water
Measure the change in volume (final volume - initial volume)
The volume of displaced water is equal to the volume of the object
Density = Mass / Volume
2
Q
define pressure and an example
A
- force per unit area (Pascals, Pa)
- e.g lying down on a bed nails
- force applied is your whole body
- total area is either - a single pinpoint/ many points spread of large area
3
Q
explain how gas exerts pressure
A
- exert pressure due to collisions between gas molecules RANDOMLY + wall (brownian motion)
- acts in all directions equally
- when molecules bounce off walls = change direction = force
- velocity + momentum changes
4
Q
explain absolute zero and describe Kelvin scale of temp
A
- the temp at which pressure is zero = absolute zero (-273ºC)
- particles have no KE + motionless
- temp in kelvin scale = temp in degrees Celcius +273
5
Q
how does changing temp of gas affect vel of particles
A
- the higher the temp = more KE particles have —> faster avg vel of particles
6
Q
how does temp affect pressure of a gas
A
- increasing temp = increase KE —> move faster
- particles collide harder & more frequently = increased pressure by exerting a force
7
Q
how does changing vol of gas affect pressure of gas
A
- vol + pressure –> inversely proportional ( if temp + mass is kept constant )
- if vol decreases —> gas compressed = pressure increases
- if vol increases (gas expands) = pressure decreased
8
Q
in a pump , how does pressing piston = increase in temp
A
- pressing = decreased vol
- increased pressure
- particles collide more frequently
- velocity of particles increase
- temp increases —> gain KE
9
Q
Explain the pattern of the paths of water from the tube
A
- water at bottom has greater pressure = pressure increaes with depth
- force on water is greatest at bottom
