Chemistry: Post your doubts here!

[Amy Bloom]

1. YOu are right that is because of isotopes..
2. I dont get your question

For 2: these are isotopes of oxygen namely O-16, O-17 and O-18.

 

[Amy Bloom]

Your order of reaction for [NO] is wrong, it is not 0, it is 2
Check experiments 1 and 2:
[H+] is constant so lets check [NO]
[NO] increases 2 times and the rate increases (0.013/0.0033) = 4 times which is 2^2 times
Therefore order of reation w.r.t [NO] is 2
Iam sure you can solve rest of the parts easily...

Thanks a lot for clearing that for me. ^_^
Humm... why that 2^2 part?

 

[Amy Bloom]

Oh yeah!! I totally forgot about the chiral centre part! *facepalm*
Thanks a lot for clearing that out for me Amy!

u're welcome. ^_^

 

[DragonCub]

help
Which element has an equal number of electron pairs and of unpaired electrons within orbitals of
principal quantum number 2?
A beryllium
B carbon
C nitrogen
D oxygen

the marking scheme ans is D
and im kinda new 2 all this site handling so just cope up with me k

The "orbitals of principal quantum number 2" refers to the electrons in the 2nd energy level.
Beryllium has 2 electrons on the 2nd level which are lone electrons. That is 0 pairs & 2 unpaired. A is incorrect.
Carbon has 4 electrons on its 2nd level. Two of them are paired. So it is 1 pair & 2 unpaired. B is incorrect.
Nitrogen has 5, two of which are paired - 1 pair & 3 unpaired. C is incorrect as well.
Oxygen has 6, four of which are paired - 2 pairs & 2 unpaired. The number is the same now, so D is correct.

 

[samwickz]

The "orbitals of principal quantum number 2" refers to the electrons in the 2nd energy level.
Beryllium has 2 electrons on the 2nd level which are lone electrons. That is 0 pairs & 2 unpaired. A is incorrect.
Carbon has 4 electrons on its 2nd level. Two of them are paired. So it is 1 pair & 2 unpaired. B is incorrect.
Nitrogen has 5, two of which are paired - 1 pair & 3 unpaired. C is incorrect as well.
Oxygen has 6, four of which are paired - 2 pairs & 2 unpaired. The number is the same now, so D is correct.

ahhhh still lyk greeeeeek Sorry so can u lyk explain it a inzywinzy bit more pretty plz

 

[smzimran]

Thanks a lot for clearing that for me. ^_^
Humm... why that 2^2 part?

2nd order means rate = [conc.]^2 you may check it in a book...
order corresponds to power of the conc. of reactant

 

[Amy Bloom]

2nd order means rate = [conc.]^2 you may check it in a book...
order corresponds to power of the conc. of reactant

Thank you. ^_^

 

[Mustehssun Iqbal]

Assalamu alaikum,
This questions is about Atoms, moles and stiochiometry;
Q) On heating, 0.02 mol of the elementM reacts with 0.025 mol of oxygen gas. What is the empirical formula of the oxide of M??
A. M2O
B. M2O5
C. MO4
D. M2O5
E. MO5
Correct answer is D.

 

[smzimran]

Assalamu alaikum,
This questions is about Atoms, moles and stiochiometry;
Q) On heating, 0.02 mol of the elementM reacts with 0.025 mol of oxygen gas. What is the empirical formula of the oxide of M??
A. M2O
B. M2O5
C. MO4
D. M2O5
E. MO5
Correct answer is D.

xM + (y/2)O2 --> MxOy
We know that
x = 0.02 and y/2 = 0.025
y = 0.05
The compound is
M(0.02) : O(0.05)
Reduce to simplest terms to get
M2O5

 

[Mustehssun Iqbal]

thanks again!

 

[CaptainDanger]

9701_s11_qp_33.pdf
9701_s11_ms_33.pdf

I don't get Q2 b i) and ii) ?

 

[KareemMokhtar]

Can anyone link me to old papers that are not available in the Papers Section? anything before June 2002 will do. Thank you!

 

[Anonymous']

Can anyone link me to old papers that are not available in the Papers Section? anything before June 2002 will do. Thank you!

anything before June 2002? November 2001 is available in the Papers section.

 

[Muhammad Bin Anis]

help
Which element has an equal number of electron pairs and of unpaired electrons within orbitals of
principal quantum number 2?
A beryllium
B carbon
C nitrogen
D oxygen

the marking scheme ans is D
and im kinda new 2 all this site handling so just cope up with me k

Got it ...
Look the question asks for the paired and unpaired electrons of orbitals of Principal Quantum Number 2
So just go for shell 2
elctronic configuration of O = 1s2 2s2 2p4
considering 2 only
u have 2s2 and 2p4
2s2 is apair no doubt
but 2p4 has one paired group and two individuals so that mkes two paired and two unpaired in 2 orbital

 

[samwickz]

Got it ...
Look the question asks for the paired and unpaired electrons of orbitals of Principal Quantum Number 2
So just go for shell 2
elctronic configuration of O = 1s2 2s2 2p4
considering 2 only
u have 2s2 and 2p4
2s2 is apair no doubt
but 2p4 has one paired group and two individuals so that mkes two paired and two unpaired in 2 orbital

O-M-G thanx alot yeyyyyy i got it @ last woha thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u thank u
thank u thank u thank u thank u SOOOOOOOOOOOOOOOOOO MUCH! UR D BEST

 

[hassam]

lolx

 

[CaptainDanger]

*Which one these always applies to a nucleophile?

A) It attacks a double bond.
B) It has a lone pair of electrons.
C) It has a single atom.
D) It is negatively charged.

Why its not D?

 

[Sabcore]

Hey guys, I need that explained. I don't have an idea how to do this whole question. Someone please explain to me in clear details if possible on how to solve this question. I need this by tomorrow.

Thanks.

 

[Dayyanah]

I need help with mass spectrometer in applications... how do u draw the peaks n how are their heights calculated?

 

[smzimran]

Hey guys, I need that explained. I don't have an idea how to do this whole question. Someone please explain to me in clear details if possible on how to solve this question. I need this by tomorrow.

Thanks.

(a) You may use the method in which you put your reacting flask on an electronic balance and measure the rate of decrease of mass as brown N2 gas escapes, i am not giving the details of this procedure, i hope you know it.

(b) check the initial rates
It is 7 when 0.01 mol/dm3 is used and
it is 3.5 when 0.005 mol/dm3 is used
We can see that as concentration increases by 2, the rate is also doubled
Therefore, the order of reaction is 1

(c) Increasing temp should increase rate as a higher temp means that reacting particles will have greater energy and so, more effective collisions take place which increases rate of production of products...