GASEOS STATE
1. applications of boyle's law :
* proves gases are compressible, the more it is pressed the denser it becomes
* explains why mountaineers carry oxygen
2. applications of charle's law :
* explains why air expands on heating
* hot air is lighter - fact used in hot air baloons
3. applications of dalton's law of partial pressures
* to find pressure of dry gas
4. avogadro's law
* also called limiting law bcoz it exits only in the limit of extremely low pressure
5. applications of graham's law of diffusion
* separation of isotopes of same element
6. Atmolysis - process of separation of two gases on the basis of different rates of diffusion due to difference in densities
7. Loschmidt number - number of molecules in 1 cc of a gas at stp. ( value = 2.617 * 10^ 19/cc
8. compressibility factor (Z) - extent of deviation
* for ideal gas Z=1
* for negative deviation , Z<1 ; gas is more compressible than expected ideal behavior (eg methane,CO2,N2)
* for positive deviation , Z > 1 ; gas is less compressible than expected ideal behavior (eg H2,O2,He)
* exceptional behavior of H2 & He
their Z always > 1 and increases with increase of pressure bcoz they are small molecules & intermolecular forces of attraction are negligible
P( V - b) = RT
PV/RT = 1 + Pb/RT , So Z > 1
9. easiest way to liquify a gas is to lower the temperature and increase the pressure
10. for a van der waal's fliud , a/b has dimensions of energy per mole .
11. two gases at same temp. and pressure diffuses into each other due to change in entropy.
12. temp at which celcius and fahrenheit scales give same reading is -40 .
13.during compression of a gas at constant temperature , density of a gas,distance between molecules , number of collisions in 1 cm2/sec changes but avg. velocity of molecules remain the same.
14. Law of corresponding states - 2 substances with same reduced pressure and same reduced temperature, will have same reduced volume.
15. a balloon filled with ethyne if pricked with needle and quickly dropped into a tank of hydrogen gas under identical conditions , after a while the balloon will increase in size as hydogen will diffuse into the balloon .( rate of diffusion is inversely proportional to square root of molecular mass)
16. vapour pressure of a liquid depends only on temperature, nature of liquid and not on volume of container.
17 . surface tension is measured in stalgmometer.
18. size of weather balloon becomes larger and larger as it ascends into higher altitudes bcoz atm. pressure decreases. to regain equilibrium with external pressure , the gas inside expands to decrease its pressure.
19 . tyres of automobiles are inflated to lesser pressure in summers , bcoz in summers avg kinetic energy of molecules inside tyre increases and so pressure on walls increases . if pressure inside is not low , during inflation it may burst .
20 . diffusion is independent of gravitation.
21. if a liquid is heated to the critical temp. of its vapour , the meniscus between the liquid and vapour disappears. (surface tension of liquid becomes 0)
22. CO2 is used to dissolve caffeine from coffee beans . ( substitute for chlorofluorocarbons)
23. van der waals constant " a " is related to ease of liquifaction of the gas . greater the value of a , greater is the inter molecular foce of attraction and hence more easily is the gas liquified . its value is in order : SO2 > Cl2 > NH3 > HCl
24 different reagents for absorbing gas are :
WATER VAPOUR -conc. H2SO4, fused CaCl2
NH3-acid soln. / CuSO4 soln.
O3 - turpentile oil
O2 -alkaline pyrogallol
NO- FeSO4 soln.
CO- ammoniacal cuprous chloride
CO2,SO2-alkali solution
Cl2-water/ alkali soln
25 . conversions :
1m3 = 103 dm3 = 106 cm3
1 L = 103 cm3 = 1 dm3 = 10-3 m3
1 atm = 76 cm = 760 mm
1 atm = 1.01325 bar
1 bar = 0.987 atm
1 Pa = 1 N/m2
1 atm = 1.01325 * 105 Pa
1 bar = 105 Pa
Hope it proves to be useful....
plzzzz post ur comments...!!!
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