mnsr 21

Question 1

the reason why solids have definite shape

Answer 1

they vibrate gently and have organised pattern( occupy lattice structure m arranged periodically in every direction )

Question 2

atoms in crystals lattice vibrate about their

Answer 2

equilibrium lattice position

Question 3

how does the solid undergo thermal expansion

Answer 3

• temp = increases
• amplitude = increases
• frequency of vibration = increases

Question 4

the breaking of the lattice bonds between adjacent atoms is called

Answer 4

melting
- as temp continues to increase , vibrations become energetic and vigours and began to shake.

Question 5

gallium melts at

Answer 5

37 degree c aka the body temp

Question 6

liquids have

Answer 6

• no regular shape and pattern
• can be moulded
• further apart than solid but can still attract each other

Question 7

when the kinetic energy escapes from bulk liquid this process is called

Answer 7

evaporation ( the rate of evaporation increases the temp)

Question 8

molecules evaporating from liquid surface generates

Answer 8

vapor pressure
( at equilibrium the no. of molecules evaporating = the no. of vapor molecules re entering the liquid )

Question 9

the boiling point is when

Answer 9

vp increases as temp increases
the temp by which vp = p atm is the boiling point

Question 10

visible evaporation occurs through the bolt of the liquid in

Answer 10

boiling point
the boiling point is the only temp at which the liquid and vapor can coexist in equilibrium for a given pressure.

Question 11

the change of solid to liquid at the same temp is called

Answer 11

latent heat of fusion

Question 12

the change from liquid to gas at the same temp is called

Answer 12

latent heat of vaporisation

Question 13

specific latent heat of fusion ( Lf) and specific latent heat of vaporisation ( LV)

Answer 13

-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

Question 14

true or false: it takes more energy to evaporate than melt

Answer 14

true

Question 15

the body cools itself by stealing

Answer 15

latent heat of vaporisation to evaporate the sweat on the skin

Question 16

Temp at which phase change occurs, varies with the absolute pressure is called

Answer 16

phase diagram

Question 17

liquid co2 can’t exist at

Answer 17

standard atmospheric pressure

Question 18

the +ve slope of liquid-gas phase

Answer 18

• can boil water at temp less than 100 if the gas pressure is above the liquid surface is lowered

Question 19

in the flight cabin the pressure is

Answer 19

2/3 atm and water boils <100 c

Question 20

if fluid pressure increases

Answer 20

the boiling point increases

Question 21

h20 in solid liquid boundary has

Answer 21

-ve slope, aka the freezing or melting point temp increases as the pressure is reduced

Question 22

the concept of freeze drying is

Answer 22

the water freeze at temp > 0 c if we reduced the air pressure

Question 23

reduced pressure can skip the liquid phase and convert solid to gas by

Answer 23

sublimation ( as dry ice)

Question 24

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………

Answer 24

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.

Question 25

the final state of matter is called

Answer 25

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