unit five: solids, liquids and gases Flashcards
order solids, liquids and gases in order of density from high to low
solids, liquids, gases
density =
ρ =
mass / volume
m/V
what can density be measured ijn
kg/mcubed or g/cmcubed
what do you use to measure a regular solid
a half-metre rule
how do you measure the volume of a liquid displaced by an irregular solid
make sure the measuring cylinder is on a flat surface and you look at the scale straight on to avoid parallax error
how do you measure the volume of an irregular soid
measure mass using weighing scales, put in a displacement can and measure the volume of liquid displaced.
pressure =
p =
force / area
F/A
what is pressure measured in
pascals
what is force measured in
newtons
what is area measured in
square metres.
why does a stiletto or pin have more ability than your thumb
all the pressure is concentrated on one point
pressure in liquids act…
equally in all directions (as long as it isn’t moving)
what is the pressure exerted on humans by the atmosphere
about 100 000 Pa
pressure difference =
height x density x gravitational field strength
h x ρ x g
how do you convert from g/cm cubed to kg/m cubed
multiply by 1000
what is pressure
weight in newtons per metre squared acting down on a surface.
1 Pa =
1 N/m squared
solid to liquid
melting
liquid to gas
boiling
gas to liquid
condensation
liquid to solid
freezing
what is a boiling point
when a liquid becomes a gas
what is a melting or freezing point
when a solid becomes a liquid
describe the structure and position of molecules in a solid substance
the molecules in a solid are tightly packed and held in fixed positions by strong forces. the molecules can vibrate around their fixed positions. as the solid gets hotter the vibrations get bigger.
describe the structure and position of molecules in a liquid substance
closely packed
irregular structure
intermolecular forces are strong molecules move randomly.
describe the structure and position of molecules in a gas substance
widely spaced
continuous state of random motion
weak intermolecular forces except during collisions
molecules move randomly.
particles in a solid:
tightly packed
held in fixed pattern or crystal structure by strong forces
vibrate around their fixed positions
particles in a liquid:
tightly packed
are not held in fixed positions but are still bound together by strong forces
move at random with no fixed positions
particles in a gas:
are very spread out
have no fixed positions and the forces between them are very weak
move in a rapid random motion
what is specific heat capacity
the amount of energy required to increase the temperature of 1 kilogram of a certain substance by 1 degree celsius.
what is the unit for specific heat capacity
J/kg degrees celsius
what is the symbol for specific heat capacity
c
heat change =
mass x specific heat capacity x temperature change
what is the symbol for heat change
ΔQ
what is the symbol for temperature change
ΔT
1st gas law: the random motion of gas and liquid particles explains why…
pressure acts in all directions at any point
2nd gas law: the speed of molecules increases with temperature, so as we heat gases in a rigid container, more.
energetic collisions with the walls happen more frequently, raising the pressure of the gas.
3rd gas law: the temperature of a gas in Kelvin is proportional to…
the average kinetic energy of the gas molecules
what is Boyle’s law
that volume is inversely proportional to pressure.
p1 x V1 =
p2 x V2
p1/p2 =
V2/V1
what is absolute zero
when you cool a fixed mass of gas at constant volume, its pressure drops. if you continue to cool the gas below 0 degrees celsius, the pressure will keep dropping until the pressure is zero, and graphs predict that this will happen when the temperature is -273 degrees celsius, and this is the lowest possible temperature. this is called 0 Kelvin (K).
