Biology; Chemistry; Physics: Post your doubts here!

[hassan100]

what about CaO..?

CaO is also used but others are relatively used more

 

[hassan100]

Can someone tell me that is sulphuric acid used as catalyst?

 

[legion]

Can someone tell me that is sulphuric acid used as catalyst?

it is the usual acid catalyst for the conversion ofcyclohexanone oxime to caprolactam, used for making nylon. It is used for making hydrochloric acid from salt via the Mannheim process. Much H2SO4 is used in petroleum refining, for example as a catalyst for the reaction of isobutane with isobutylene to give isooctane, a compound that raises the octane rating of gasoline

 

[Vogue]

it is the usual acid catalyst for the conversion ofcyclohexanone oxime to caprolactam, used for making nylon. It is used for making hydrochloric acid from salt via the Mannheim process. Much H2SO4 is used in petroleum refining, for example as a catalyst for the reaction of isobutane with isobutylene to give isooctane, a compound that raises the octane rating of gasoline

wow! these are so difficult words that I even did not come across in Federal Chemsitry organic section.....is that all Mannheim process and isobutylene and isoocatne and cyclohexanone oxime and caprolactam(God knows how to pronounce these)part of O level syllabus?

 

[Vogue]

Can someone tell me that is sulphuric acid used as catalyst?

this acid is used as a catalyst in formation of esters.

 

[Vogue]

http://www.xtremepapers.com/CIE/Cambridge O Levels/5054 - Physics/5054_s11_qp_41.pdf
Question 3 part a of phy atp may june 11, qp 41
plz help....ms contains nothing as answer

 

[hassan100]

it is the usual acid catalyst for the conversion ofcyclohexanone oxime to caprolactam, used for making nylon. It is used for making hydrochloric acid from salt via the Mannheim process. Much H2SO4 is used in petroleum refining, for example as a catalyst for the reaction of isobutane with isobutylene to give isooctane, a compound that raises the octane rating of gasoline

these are too difficult terminologies that i havent heard of even. actually i saw a question chemstry atp regarding electrolysis in which it was written sulphuric acid is added in water for increasing the speed of electrolysis

 

[ktc]

http://www.xtremepapers.com/CIE/Cambridge O Levels/5054 - Physics/5054_w03_qp_2.pdf

Could somebody please solve Q10 (c)(ii)? I get the wrong answer. can u answer this please

i am getting 4200 it should be 8200 i dont get it

Hmm, I did it like a million times and kept getting 4200 Volts myself.

The total potential difference across the resistance of the metal sheath is:

0.8 x [0.70 x 7500] = 4200V.

And in fact that *probably* is the right answer.

‘Cuz while I was going through the marking scheme, I noticed something:
http://www.xtremepapers.com/CIE/Cambridge O Levels/5054 - Physics/5054_w03_er.pdf

Answers: (c)(i) 4000V, (ii) 8200V, (iii) 0.448W.

^ This is what’s given in the MS. However, did you realize there are (iv) parts to question 10, but only (iii) parts have answers given in the MS?

Q.10

(c)(i) The total potential difference across all the repeaters:

40 x 100 = 4000V.

Marking scheme answer => 4000V

(c)(ii) The total potential difference across the resistance of the metal sheath:

0.8 x 5250 = 4200V.

Marking scheme answer => 8200V

(c)(iii) The potential difference provided by the power supply:

4000 + 4200 = 8200V.

Marking scheme answer => 0.448W.

(c)(iv) The thermal energy (heat) lost per second from each kilometre of the metal sheath:

0.8^2 x 0.7= 0.448W.

Marking scheme answer => *not given*

I think the marching scheme accidently mixed up answer (c)(iii) [8200V] with answer (c)(ii) and answer (c)(iv) [0.448W] with answer (c)(iii). :/

[Leaving answer (c)(iv) all alone, cuz there weren’t any answers left to mix it up with too ]

I guess, an error in the MS is possible; it is prepared by human beings, after all.

 

[legion]

wow! these are so difficult words that I even did not come across in Federal Chemsitry organic section.....is that all Mannheim process and isobutylene and isoocatne and cyclohexanone oxime and caprolactam(God knows how to pronounce these)part of O level syllabus?

these are too difficult terminologies that i havent heard of even. actually i saw a question chemstry atp regarding electrolysis in which it was written sulphuric acid is added in water for increasing the speed of electrolysis

dunt worry. they arent in our syllabus. i had the same question and my brother gave me this answer (he is in engineering so he has a crack in his head ) so when u asked it i copied the same answer. in human terminology, H2SO4 it is used as a catalyst in making of nylon, making of hydrochloric acid and in cracking of petroleum.
happy now? =D

 

[ktc]

(he is in engineering so he has a crack in his head )

Hope your brother doesn’t read that

 

[Vogue]

dunt worry. they arent in our syllabus. i had the same question and my brother gave me this answer (he is in engineering so he has a crack in his head ) so when u asked it i copied the same answer. in human terminology, H2SO4 it is used as a catalyst in making of nylon, making of hydrochloric acid and in cracking of petroleum.
happy now? =D

o thank u
i am so relieved now

 

[stareaj]

How do you calculate half life

 

[stareaj]

Also can someone pls explain magnetic effect the whole chp

 

[scouserlfc]

How do you calculate half life

just half the given radiactivty like if a compound gives off 300 radiation by the end of one year it will have 150 and then u halve 150 to get for second year dont worry u are provided with the time for the half life to occur and the radiation

 

[stareaj]

I stll don't get it can u pls explain with a past paper question please explain each step to as I suck in math

 

[stareaj]

Why in the ATP chem potassium magnate co our changes from purple to pink in titration?and in exothermic reaction thus temp rise ?so in endo temp of surrounding and reaction decreases?:-/

 

[stareaj]

And I have another question lol in ATP theres this question that acid poured out of measuring cylinder with what two things should it be cleaned with the answer is water then acid can someone pls explain why it doesn't make sense I thought first alkai so that remaining acid react to form salt then wash with water to remove salt but this is wrong why.
And can someone plssssss give me. A list of compounds and their colours

 

[sweetiepie]

ATP NOTES

 

[stareaj]

But there's no mention of colours ?

 

[hassan100]

dunt worry. they arent in our syllabus. i had the same question and my brother gave me this answer (he is in engineering so he has a crack in his head ) so when u asked it i copied the same answer. in human terminology, H2SO4 it is used as a catalyst in making of nylon, making of hydrochloric acid and in cracking of petroleum.
happy now? =D

you are calling your bro crack btw thank you