Discussion [Physics]

[Daniel Koh]

Hey everyone,

Some questions for discussion. Do take note of the concepts underlying
it.

Q1. Oxygen has a boiling point of 90K and a melting point of 55K.
Describe qualitatively how oxygen at 273K and oxygen at 27K differ in
respect of

(i) density
(ii) spacing of the molecules
(iii) order in the pattern of molecules
(iv) motion of the molecules

Q2. Describe experimental evidence for the wave nature of particles
[about the diffraction through crystal?']

Q3. Outline an electrical method to determine the specific latent heat
of vaporisation of water.

Q4. Cooling water enters the heat exchanger in the turbine half of a
nuclear power station at 6.0*C and leaves at 14*C. The rate of heat
removal by the water is 6.7 X 10^9 J per minute. The specific heat
capacity of water is 4200 J Kg^-1 K^-1

Q5. Which statement about the evaporation and boiling of a liquid is
correct?

1. Boiling always occurs at a higher temperature than evaporation
2. Evaporation occurs at any temperature, but the boiling point
depends on the external pressure.
3. Evaporation results in the loss of the most energetic molecules
from a liquid but, in boiling, all molecules have the same energy.
4. The rates of evaporation and boiling are unaffected by changes in
the surface area of the liquid.

Q6. Which relationship is not correct?

1. A = Ao exp (-lt)
2. A = lN
3. A = t(1/2)N
4. N = 1.44t(1/2)A

Daniel

[dominic yong]

> From: danie...@hotmail.com
> To: a-level...@googlegroups.com
> Subject: [Work hard!] Discussion [Physics]
> Date: Sat, 13 Oct 2007 21:50:34 -0700
>
>
> Hey everyone,
>
> Some questions for discussion. Do take note of the concepts underlying
> it.
>
> Q1. Oxygen has a boiling point of 90K and a melting point of 55K.
> Describe qualitatively how oxygen at 273K and oxygen at 27K differ in
> respect of
>

> (i) density(at 273k lower density...i think and at 27k more dense...if not both will e the same)
> (ii) spacing of the molecules(at 273k its far and at 27k its close)
> (iii) order in the pattern of molecules(at 273k its random and at 27 its high)
> (iv) motion of the molecules(at 273k there is motion and at 27k there issint)

>
> Q2. Describe experimental evidence for the wave nature of particles

> [about the diffraction through crystal?'](this one not sure...please tell me the answer)

>
> Q3. Outline an electrical method to determine the specific latent heat

> of vaporisation of water.(q=mc(T1-T2),make c the subject?haha not sure what you mean y the question)

>
> Q4. Cooling water enters the heat exchanger in the turbine half of a
> nuclear power station at 6.0*C and leaves at 14*C. The rate of heat
> removal by the water is 6.7 X 10^9 J per minute. The specific heat

> capacity of water is 4200 J Kg^-1 K^-1(..... so wats the question??)

>
> Q5. Which statement about the evaporation and boiling of a liquid is

> correct?(don't blame me if i am wrong arh)
>
> 1. Boiling always occurs at a higher temperature than evaporation(yes)

> 2. Evaporation occurs at any temperature, but the boiling point

> depends on the external pressure.(yes)

> 3. Evaporation results in the loss of the most energetic molecules

> from a liquid but, in boiling, all molecules have the same energy.(yes)

> 4. The rates of evaporation and boiling are unaffected by changes in

> the surface area of the liquid.(no.they are affected)

>
> Q6. Which relationship is not correct?
>
> 1. A = Ao exp (-lt)
> 2. A = lN

> 3. A = t(1/2)N(this one should be A=In2/t(1/2)xN)