Unit 3

Question 1

What are the four type of solids?

Answer 1

1. Molecular solids: Molecules held together by intermolecular forces
2. Covalent solids: Extended structures held together by covalent bonds
3. Ionic solids: Held together by electrostatic forces
4. Metallic Solids : Metallic bond atoms, metal atoms as cations in the sea of ‘delocalized’ electrons

Question 2

What is surface tension?

Answer 2

Amount of energy required to expand a liquid surface

Question 3

What causes surface to contract?

Answer 3

Intermolecular attractions from below

Question 4

What happens if surface tension is less?

Answer 4

IT occupies more area

Question 5

What is cappilary action?

Answer 5

Rising of a liquid in a narrow space against the pull of gravity

Question 6

What are the two types of forces liquids in a container face?

Answer 6

Cohesive forces: Forces between molecules

Adhesive forces: Forces aganist the wall like H and Sio2

Question 7

What are the phase changes?

Answer 7

Solid —> liquid: Fusion (opp, freezing)
Liquid —–> vapour: Vapourisation (Condensation)

Solid —-> Gas: Sublimation (opp, deposition)

Question 8

What happens to energy while braking bonds?

Answer 8

Energy is supplied, endothermic

To make bonds, energy is removed, exothermic

Question 9

How is Enthalpy of Vapourazation compare to fusion?

Answer 9

delta H vap > delta H fus

Question 10

When is a phase change spontaneous?

Answer 10

if free energy is negative.

Delta G = Delta H - T.deltaS

Question 11

What determines if a process is spontaneous?

Answer 11

Both Delta H and delta S

Question 12

When is entropy more?

Answer 12

If there is more randomness

S disordered > S ordered

H2O (s) ———-> H2O (l)

Delta S = S final - S initial

Question 13

What happens if Delta S = S final - S initial = -ve?

Answer 13

The reaction will be spontaneous

Question 14

How do you find the molecules with highest boiling points?

Answer 14

The one with the strongest intermolecular force is the one with highest boiling point

Question 15

What is vapour pressure?

Answer 15

The pressure of gas in equilibrium (co-existing) with its liquid (or solid) at a specified temperature

Question 16

What happens to vapour pressure with temp?

Answer 16

increases

Question 17

What is boiling point?

Answer 17

The temperature at which vapour pressure of a liquid equals the external pressure.

Question 18

What is normal boiling point?

Answer 18

boiling point at 1 atm.

Question 19

What does vapour pressure depend upon?

Answer 19

Temp and strength of intermolecular forces

Question 20

What determine the state of matter?

Answer 20

Intermolecular forces

Question 21

What is equalization of pressure?

Answer 21

P atm = Phg

Question 22

What happens to height if the density is more in a manometer?

Answer 22

The height increases

P = density.gravity.height of hg

Question 23

What are the macroscopic properties of a compound?

Answer 23

T, V, n , P

Question 24

What does the ideal gas law state?

Answer 24

1. Gases are made up of tiny particles moving completely randomly.
2. Total volume of particles very small compared to the size of container.
3. Particles do not interact with each other.
4. Particle collisions are elastic (no energy lost)
5. Kinetic energy (K.E) increases with temp.

Question 25

What is avg.KE for mol of gas?

Answer 25

K.E = 3RT/ 2Na ——> J/mol

Question 26

How do you find the speed of particle?

Answer 26

u = root(3RT/M)

Question 27

How is pressure created?

Answer 27

From gas particles colliding with container walls

Question 28

When T and n is constant, How are P and V related?

Answer 28

V is inversely proportional to P

Question 29

When P and n are fixed, how does V and T change?

Answer 29

V is directly proportional to T

Question 30

How can you find mole fraction?

Answer 30

Xo2 = # mol of o2/ total moles

or

Po2/ Total P

Question 31

What’s the differences in Effusion and Diffusion?

Answer 31

Effusion: Escape of gas through a hole

Diffusion: Movement of one gas through another.