mnsr 21 Flashcards
the reason why solids have definite shape
they vibrate gently and have organised pattern( occupy lattice structure m arranged periodically in every direction )
atoms in crystals lattice vibrate about their
equilibrium lattice position
how does the solid undergo thermal expansion
- temp = increases
- amplitude = increases
- frequency of vibration = increases
the breaking of the lattice bonds between adjacent atoms is called
melting
- as temp continues to increase , vibrations become energetic and vigours and began to shake.
gallium melts at
37 degree c aka the body temp
liquids have
- no regular shape and pattern
- can be moulded
- further apart than solid but can still attract each other
when the kinetic energy escapes from bulk liquid this process is called
evaporation ( the rate of evaporation increases the temp)
molecules evaporating from liquid surface generates
vapor pressure
( at equilibrium the no. of molecules evaporating = the no. of vapor molecules re entering the liquid )
the boiling point is when
vp increases as temp increases
the temp by which vp = p atm is the boiling point
visible evaporation occurs through the bolt of the liquid in
boiling point
the boiling point is the only temp at which the liquid and vapor can coexist in equilibrium for a given pressure.
the change of solid to liquid at the same temp is called
latent heat of fusion
the change from liquid to gas at the same temp is called
latent heat of vaporisation
specific latent heat of fusion ( Lf) and specific latent heat of vaporisation ( LV)
-the energy required to change from 1kg of a solid to 1 kg of liquid at the same temp
- the energy required to change from 1kg of liquid to 1kg of gas at the same temp
true or false: it takes more energy to evaporate than melt
true
the body cools itself by stealing
latent heat of vaporisation to evaporate the sweat on the skin
Temp at which phase change occurs, varies with the absolute pressure is called
phase diagram
liquid co2 can’t exist at
standard atmospheric pressure
the +ve slope of liquid-gas phase
- can boil water at temp less than 100 if the gas pressure is above the liquid surface is lowered
in the flight cabin the pressure is
2/3 atm and water boils <100 c
if fluid pressure increases
the boiling point increases
h20 in solid liquid boundary has
-ve slope, aka the freezing or melting point temp increases as the pressure is reduced
the concept of freeze drying is
the water freeze at temp > 0 c if we reduced the air pressure
reduced pressure can skip the liquid phase and convert solid to gas by
sublimation ( as dry ice)
If we remove nearly all the heat energy from a small group of inert atoms we end up with a Quantum Mechanical state called a………
Bose-Einstein Condensate (BEC)
- At micro-Kelvin Temperatures, the Pauli-Exclusion Principle is relaxed. Atoms occupy identical ground states and get as close to each other as Heisenberg Uncertainty Principle allows.
the final state of matter is called
plasma
- when so much energy is supplied that all electrons are ionised off
- plasma is a rarified gaseous soup og positive and -ve ions
- highly reactive in physio/chemical environment
- used for disinfection
- example of plasma : aurora borealis aka australis
