Topic 7 - Matter Flashcards
What are the arrangements of particles in solids liquids and gases
- Particles in a: gas are well separated with no regular arrangement.
- liquid are close together with no regular arrangement. weaker forces of attraction compared to solids
- solid are tightly packed, usually in a regular pattern. strong forces of attraction little kinetic energy so vibrate in their fixed positions
What is the formula for density
mass/volume
Density does vary with …. or……
size or shape
How can you find the density of an irregular solid
measure mass on balance
using a displacement can measure volume of water displaced
Why do solids liquids and gases have different densities
- when a substance changes state although its mass doesnt change, its volume does, so since the volume changes the value for density changes too
- Solids are more dense
What does heating a substance do to energy stores
increases energy in thermal energy store
What is specific heat capacity
and equation
The amount of energy needed to change 1 kg of a substance to warm up by 1 degrees.
Change in thermal energy=mass x SHC x temp change
Describe an experiment to measure SHC of water
- measure mass of insulating container
- fill with water and measure mass again, the difference in mass is mass of water in container
- add joulemeter to electric immersion heater
- measure the initial temp then turn on power
- when temp increased by 10 degrees, record the energy on joule meter and increase in temp
- rearrange equation and repeat 3 times to find average
What is Specific latent heat
amount of energy needed to break bonds and change 1kg of a substances state
Why does temperature not change during a state change
because bonds breaking/forming so energy is used to use of release energy rather than increase the temperature
describe an experiment used to measure SPL
- fill beaker with crushes ice (can insulate with lid)
- place thermometer and record temp of ice
- gradually heat with bunsen
- every 20 seconds record temperature
- continue until boiling
- plot graph of temp against time
Whats the equation for SPL
Thermal energy = mass x SLH
how is pressure created
by colliding gas particles exerting a force
eg)in an enclosed system gas particles colliding with walls
Name Two factors which effect gas pressure
increasing temperature increases pressure as particles have more energy in their kinetic stores so collide more
-increasing volume decreases pressure as particles get more spread and our less likely to collide
What is absolute zero
the lowest amount of energy possible in their kinetic stores.
0kelvin and -273degrees
Why can a change in pressure cause a change in volume
with containers without a fixed volume like a balloon, the volume of gas is constant–so its not expanding or contracting when pressure pushing out is same as pressure pushing in
Explain changing the pressure inside a container by heating or cooling
With balloon
If balloon is heated- particles gain energy and move quicker so more pressure inside balloon.
since the outward pressure of balloon is greater than inward, the balloon expands until balanced out
Explain how you can change the external pressure on a gas
-pushing on a plunger increases inward pressure by giving particles a smaller volume to collide in
Why does does work on a gas increase its temperature
Because it increases its internal energy, which increases its pressure
eg) can be done mechanically with bike pump
transferring energy to kinetic store which inc. inetrnal energy and heats
what does it mean if an object has been elastically distorted?
It means it cant return to its original shape and length after the force has been removed
what is an elastic limit
point where object stops distorting elastically and begins to distort inelastically
what is a plastic limit
when the object acts as a plastic and eventually snaps
if work is done on a spring where is energy transferred
elastic potential energy store
what its Hookes law
force = spring constant x extension
What is it called when an object stretches more for each unit of force
limit of proportionality
when graph becomes non-linear
Describe an experiment to link force and extension
- measure natural length of spring with millimeter ruler clamped to stand
- add mass to spring and allow spring to rest then measure new length
- repeat process until you have 6 or more measurements
- plot force by extension graph
how do you calculate work done by a spring
energy transferred in stretching =
1/2 x spring constant x extension
how do you calculate pressure
force / area
what does fluid pressure depend on
depth and density
as depth increases so does pressure as number of particles above that point increases
how does pressure and density vary in water
pressure increases with depth
density is the same everywhere
Equation for pressure in column of liquid=
height x density x GFS
what is the resultant force called when when force exerted on bottom of object is greater than force on top
upthrust
what is upthrust equal to in fluids
the weight of fluid displaced by object
what makes an object float
if the volume of water displaced is equal to or more than its weight
usually if an object is less dense than the fluid its in then it floats
how do submarines make use of upthrust
to sink they have large tanks filled with water to increases weight so its more than the upthrust
to rise the tanks are compresses with air to reduce weight so its less than upthrust
what does atmospheric pressure decrease with
height / altitude
as altitude increases fewer air molecules are able to collide with surface as the atmosphere gets less dense
and weight above air decreases too
How is atmospheric pressure created
by air molecules colliding with surface
