Chemistry: Post your doubts here!

[Bilal Khan]

Yes but whenever I do the test for gases, take burning splint and so on, all the gas liberates and I have mix the solutions again. Any way to prevent this? Thank you for replying.

That merely depends on your practice or handling skills . Take a larger volume so that more gas liberates or you can try bringing the test tube close to a lit bunsen burner.

 

[huh]

That merely depends on your practice or handling skills . Take a larger volume so that more gas liberates or you can try bringing the test tube close to a lit bunsen burner.

Ok. Thank you very much.

 

[Bilal Khan]

Ok. Thank you very much.

Anytime , my friend .

 

[RoOkaYya G]

Yes but whenever I do the test for gases, take burning splint and so on, all the gas liberates and I have mix the solutions again. Any way to prevent this? Thank you for replying.

jst block the mouth of the test tube with ur thumb until u light a splint. the gas wont escape.
n yeah try make larger volume of solutions...itll yield more gas.

 

[MYLORD]

Who is giving chemistry p-33 tomorrow ?

 

[RoOkaYya G]

Who is giving chemistry p-33 tomorrow ?

me .-.

 

[Thought blocker]

Alright. Incase of Nitrogen, the N-N bond energy is given as 944 in the data booklet. But in the marking scheme it is taken as 994. Which one is correct?

This is not possible. Which paper is like this?

 

[Metanoia]

Alright. Incase of Nitrogen, the N-N bond energy is given as 944 in the data booklet. But in the marking scheme it is taken as 994. Which one is correct?

The values might be different due to the different editions of data booklets.

 

[Thought blocker]

The values might be different due to the different editions of data booklets.

Why does it differ? :/

 

[Metanoia]

Why does it differ? :/

I can't say for sure why it differs in this specific case.

I were to guess, it could be that recent experiments and calculations done in the labs gave a more updated value.

 

[Thought blocker]

I can't say for sure why it differs in this specific case.

I were to guess, it could be that recent experiments and calculations done in the labs gave a more updated value.

As per my thinking, its her reading mistake. That's it.
Let's see.

 

[Thought blocker]

I can't say for sure why it differs in this specific case.

I were to guess, it could be that recent experiments and calculations done in the labs gave a more updated value.

As per my thinking, its her reading mistake. That's it.
Let's see.

Recent booklet 2014 : http://www.cie.org.uk/images/95996-2014-syllabus.pdf Same value, no change seen N=N bond energy remains 944 kJ/mol.

 

[Metanoia]

As per my thinking, its her reading mistake. That's it.
Let's see.

It really depends on the years, last time it was 994. For example, qn 19 of 2003.

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w03_qp_1.pdf

It became 944 in the more recent years.

 

[Thought blocker]

It really depends on the years, last time it was 994. For example, qn 19 of 2003.

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w03_qp_1.pdf

It became 944 in the more recent years.

For now, it remains same.
Thanks for the effort.

 

[Metanoia]

For now, it remains same.
Thanks for the effort.

Yup. That's my point. For students attempting much older past year papers, they will see that the bond value of N2 is 994 instead of 944.

There's no need to be alarmed or overthink, the concepts and applications remains the same. Good luck!

 

[RoOkaYya G]

The values might be different due to the different editions of data booklets.

mark scheme is more likely to hve errors than data booklet

 

[Thought blocker]

mark scheme is more likely to hve errors than data booklet

Aw, adulto.

 

[Camille96]

Hi everyone. Does chemistry paper 3 has a huge effect on the overall grade? For example, if a student did not do well AT ALL in P3, can he/she catch up on the rest of the chemistry papers to get at least a B or A? I know A* is out of question in this case.

 

[Lily9605]

I've a doubt in paper 5 can anyone help me?

 

[bludlynsolja]

Hi! to be honest, all the papers have a significant effect on the overall result.
but obviously the other 2 papers are more weighty. paper one comprises of 31% of tbe total and paper 2 46% of the total, the remaining 23% is what the p3 or practical paper consists of.
from my past experience and my very limited knowledge, i would advise people to work hard for the practicals coz you know it is the only paper where you are sure of scoring marks. see, i agree that it is not completely a stroll in the park with the structured paper, but its mostly, following instructions given in the practical and most of all: TRUSTING YOUR WORK MORE THAN EVEN YOUR NEAREST NEIGHBOUR!!
But, since u feel that u got no hope with it, and this could be due to various factors like thinking your working was wrong while discussing after the exam with your friend, i think you should still have hope if thats the reason for despair coz in practicals, no bodies answer is certainly correct, so u may be right while they are wrong BUT in any case, if you do feel certain that u have no hope, then working hard for the other 2 papers is going to be a massive boost and u can still get an A no doubt at all.
for instance if u struggle real hard and are able to get 40 out of 46 in practicals and then maybe 20 out of 31 in the mulitple choice( u can infact even get 25 and above provided u utilize ur time well since i believe u will have around a fortnight to study for the multiple paper so u can do as many papers as is there. then i think u can score a 25) , zo u will have a 65 out of 100 un ur belt already from these two papers, and i am sure in practical u wont get lower than a 10 out of 23, so all those added up gives 75 percent.
then the thresholds come into play, if the thresholds are low, then the 75 percent might even be equivalent of an A so u are sorted.
this is from the very little knowledge and experience i have like i said earlier.
P.S for the multiple choice questions i would recomend that u see the topical questions, they really helped me as they are mulitple questions based on each topic, i am sure u must have seen em!