States of matter

Question 1

Atmospheric pressure is measured by

Sample pressure is measured by

Answer 1

Barometer

Manometer

Question 2

Relation between atm, torr, Pa, bar, dynes

Answer 2

1 atm = 760 torr = 1.013*10^5 Pa , 1 bar = 0.987 atm

Question 3

Which block defines 1 Kg

Answer 3

Pt - Ir alloy at sevres outside Paris

Question 4

Boyle’s Law
Charles’ Law
Gay-Lussac Law
Avagadro Law

Answer 4

PV = constant
V/T = constant
P/T = constant
V/n = constant

Question 5

STP values
NTP values
SATP values

Answer 5

T = 273.15K P = 1 bar V = 22.7 lit/mol
T = 273.15K P = 1 atm V = 22.4 lit/mol
T = 298.15K P = 1 bar V = 24.7 lit/mol

Question 6

Units of R ( universal gas constant) in
L - atm / K - mol
J / K - mol

Answer 6

0. 0821

8. 314

Question 7

Rate of diffusion proportionality
Temp , density , Molecular weight , Pressure , Velocity
Vapour Density ,Volume , moles , weight

Answer 7

Directly to Pre , vel , Vol , moles , root T
Inversely to root density , root Molecular weight
root VD , weight

Question 8

Aqueous tension is only dependent on

Answer 8

Temperature

Question 9

State Kinetic Gas equation and explain the terms

Answer 9

PressureVolume = 1/3 (mass of 1 molecule)(no of molecules) C ^ 2

Question 10

explain boltzmann’s constant ( k )

Answer 10

k = R ( universal gas constant ) / avagadro number
k = 1.38 * 10 ^ -23 J/K - mol

Question 11

What happens to velocity distribution curve when temperature is increased ( Cp , C bar , Crms )

Answer 11

Curve flattens and shifts to right ( higher velocity )
fraction of molecules with low velocity decreases
fraction of molecules with high velocities increases

Question 12

What is Boltzmann’s factor

Answer 12

Ratio of ni and n also called fraction of molecules having particular energy
ni/n = e ^ ( -E/kT )

Question 13

value of Cp C bar and Crms

Answer 13

Cp = (2RT/M)^1/2,
C bar = (8RT/piM)^1/2
Crms = (3PV/M)^1/2

Question 14

what happens to velocity distribution curve when Molecular mass is increased

Answer 14

Curve sharpens and shifts towards left
fraction of molecules with low velocity increases
fraction of molecules with high velocity decreases

Question 15

Which is the most ideal gas

Answer 15

Helium

Question 16

Perfect gas has energy only from ?

Answer 16

Kinetic energy of motion nothing from potential energy

Question 17

How are Real gases different from perfect gases

Answer 17

they have intermolecular interactions which alter the bulk properties

Question 18

How do intermolecular interaction affect the gas at different distances

Answer 18

At large distances energy lowering interactions dominate

at short distances energy raising repulsions dominate

Question 19

In what circumstances does a real gas behave ideally

Answer 19

High Temperature and Low Pressure

Question 20

What is compressibility factor ( Z )

Answer 20

Used to measure deviation form ideal behaviour

Z = V real/ V ideal = PV/nRT

Question 21

What are value of Z at different pressures

Answer 21

Z > 1 at high pressure ( dominant repulsive interactions)
Z < 1 at intermediate pressure ( Dominant attraction )
For H2 and He ( dominant repulsive ) at all pressures due to small size
Z = 1 at low pressure

Question 22

At what temperature does N2 gas show almost ideal behaviour

Answer 22

50 Degree centigrade

Question 23

Define Boyle temperature

Answer 23

Temp at which real gases behave as ideal gases over a wide range of pressures

Question 24

What happens when pressure is changed below and above Boyle temperature

Answer 24

Above boyle temperature, Z > 1

Below Boyle temperature, Z < 1 at first reaches minimum then increases

Question 25

What do a and b in Van der waals equation signify

Answer 25

a is the pressure correction constant and is the measure of intermolecular ATTRACTIONS
a is directly prop to liquefaction
b is excluded volume it is 4 times the actual volume of molecules of gas